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A CONCRETE STOICHIOMETRY UNIT
FOR HIGH SCHOOL CHEMISTRY

BY

Jennifer Louise Pakkala

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

DIVISION OF SCIENCE AND
MATHEMATICS EDUCATION

2006

ABSTRACT
A CONCRETE STOICHIOMETRY UNIT FOR HIGH SCHOOL CHEMISTRY
By
Jennifer Louise Pakkala

Stoichiometry is the study of quantitative relationships that exist in reactions and
is traditionally difficult for students to master. The main obstacle to a thorough
understanding of stoichiometry is that the topic is abstract, being taught at the
symbolic level. In addition, we suspect many of the students (roughly 50%) have
not yet reached the final stage of cognitive development, formal operations. These
students are unable to understand material taught at the abstract level. Therefore it
is necessary to develop models and activities that allow these students to move
from the concrete level to the abstract level.

Models were developed and implemented to assist concrete Ieamers. The most
effective activity involved a hamburger sandwich analogy built on the students’
previous knowledge of fast food. Hamburger models were built and used in
instruction so that students could rearrange the pieces and gain an understanding
of molecular events by using a macroscopic model.

The incorporation of the concrete models into the instmction of stoichiometry
proved to be successful with an average improvement of 70% between pre and
post tests. The largest improvement for an individual student was 90%. High
school students show improved understanding of chemical reactions and

stoichiometry when taught with some concrete tools.

TABLE OF CONTENTS

List of Tables .......................................................................................... v
List of Figures ........................................................................................ vi
Introduction ............................................................................................. 1
Rationale for Study ........................................................................... 1
School Demographics ....................................................................... 2
Summary of Science Taught ............................................................ 3
Theoretical Framework ..................................................................... 5
Implementation ..................................................................................... 18
Unit Objectives ................................................................................ 19
Phase 1 Implementation ................................................................. 20
Phase 2 Implementation ................................................................. 24
Phase 3 Implementation ................................................................. 27
Phase 4 Implementation ................................................................. 29
Phase 5 Implementation ................................................................. 29
Phase 6 Implementation ................................................................. 32
Results/Evaluation ................................................................................ 35
Introductory Survey ......................................................................... 35
Pre-Test .......................................................................................... 37
Post-Test ......................................................................................... 37
Post-Test Item Analysis .................................................................. 39
Exit Surveys .................................................................................... 41
Discussion and Conclusion .................................................................. 47
Appendices ........................................................................................... 53
Appendix A: Classroom Activities ................................................... 53

l. Burger Chem Formulas and Equations .......................... 54

ll. Burger Chem Mass Conservation .................................. 60

III. Balancing Equations Race ............................................. 63

IV. Types of Reactions Grid ................................................. 66

V. Burger Chem Limiting Component ................................. 68

VI. Burger Chem Yield ......................................................... 71

Appendix B: Laboratory Experiences ............................................. 75

l. Types of Chemical Reactions ........................................ 76

ll. Recycling Copper ........................................................... 82

III. S’more Lab ..................................................................... 87

IV. Percentage Yield Lab ..................................................... 91

Table of Contents Continued

Appendix C: PowerPoint® Presentations ....................................... 96
li Symbols Used in Chemical Equations ........................... 97
Activity Series ............................................................... 104

III. Introduction to Stoichiometry ........................................ 107

IV. Stoichiometry ................................................................ 112

V. Limiting Reactant and Percent Yield ............................ 116
Appendix D: Assessments ............................................................ 121
l. introductory Survey ...................................................... 122

ll. Pre-Test ........................................................................ 123

Ill. Symbol Story Rubric ..................................................... 127

IV. Section 1 Exit Survey ................................................... 128

V. Section 2 Exit Survey ................................................... 129

VI. Post-Test ...................................................................... 130
Vll.Test Self-Evaluation ..................................................... 133

VIII. Weekly Reflections ..................................................... 134

IX. Consent Letter .............................................................. 135
Bibliography ........................................................................................ 137

LIST OF TABLES

Table 1: Phases of Instruction .............................................................. 19
Table 2: Burger Chem Recipes ............................................................ 22
Table 3: Introductory Survey Data ................ l ........................................ 3 5
Table 4: Summary of Skill Responses for Exit Survey 1 ...................... 42
Table 5: Summary of Activity Responses for Exit Survey 1 ................. 43
Table 6: Summary of Skill Responses for Exit Survey 2 ...................... 43
Table 7: Summary of Activity Responses for Exit Survey 1 ................. 45

LIST OF FIGURES

Figure1: Sample Problem ....................................................................... 7
Figure 2: Stick Figure Model ................................................................. 25
Figure 3: Pre-Testhost—Test Comparison ........................................ 37
Figure 4: Post-test Response Comparison by Item Number ............... 38

vi

INTRODUCTION
Rationale for Study

The chemistry topic covered within this study, reactions and stoichiometry, was
chosen as a focus because it is one of the most important topics taught in general
chemistry, yet is difficult for students to master. When asked to rank chemistry
topics in terms of importance, a group of college professors ranked stoichiometry
fourth out of twenty-two topics that should be taught to students in high school
chemistry (Deters, 2003). Stoichiometry is the study of quantitative relationships
that exist in chemical formulas and reactions. An understanding of reactions is
necessary because a chemical equation must be properly balanced in order to be
successful in solving stoichiometry problems. Stoichiometn'c calculations are
important because they enable chemists to determine the exact amounts of
reactants and products in a chemical reaction. Stoichiometry answers the question
“how much of this reactant do I need?” or “how much product will I get?” Moreover,
stoichiometry is important to the chemistry student bewuse any career that relies
on chemistry, from pharmacist to chemiwl engineer, will require a solid
understanding of stoichiometry.

Stoichiometry is traditionally difficult for students to master. Steiner (1986)
writes that one possible reason for this difficulty is, "We introduce the topic with the
horrendous new word “stoichiometry.” Realistically, the main obstacle to a
thorough understanding of stoichiometry is that the topic is abstract. Furthermore
stoichiometry is taught at the highest level of abstraction, the symbolic level
(Gabel, 1999). In addition, about half of the students that attempt to Ieam

stoichiometry do so before they have reached the stage of formal operational
thought (Huddle, 1986 and Smith, 1978). According to Piaget's theory of cognitive
development, Ieamers should reach formal operations between the ages of 12 and
15. However, the majority of Ieamers do not reach this stage by the age of 15, as
many as 50 % of high school students have not reached formal operations (Smith,
1978). It is therefore necessary to incorporate a good deal of concrete examples
and activities when stoichiometry is first introduced. The purpose of this study was
to determine if the incorporation of some concrete learning tools coupled with
purposeful, hands-on lab experiments would help general chemistry students
understand the abstract topic of stoichiometry.
School Demggraghics

This study was conducted with students enrolled in General Chemistry, an
introductory chemistry course, at Redford Union High School in Redford Township,
Michigan. Redford Township is situated just west of the city of Detroit, the two
municipalities share a border. The Redford Union District enrolls residents from
Redford Township as well as a number of school-of-choice students who reside in
Detroit. Redford Union High School is a public school with an enrollment of 1,235
students in grades 9-12. The student body is 79 % White, 19 % Black, 1%
Hispanic, with Asian and American Indian students comprising the final 1%. The
economic level of the community is middle-class with 24 % of high school students
eligible for the free or reduced -price lunch program. The numbers for the Redford
Union District as a whole are slightly different with 35% of students in the district

eligible for free or reduwd-price lunch, similar to the state average of 36%

(Michigan Department of Education, 2006). Students that participated in the study
were eleventh and twelfth graders and ranged in age from 16 to 18 years old.
Participating students were from two different class periods. The first class period
only had a total of 10 students, and the other had a total of 21 students. Eighteen
of the 31 students enrolled in General Chemistry elected to participate in the in the
study by returning a signed consent form (Appendix D-IX).

Summary of Science Taggllt;

The focus of this study, reactions and stoichiometry, is traditionally difficult for
students to master because much of the study is at the symbolic level, rendering
the topic abstract and unreachable to some students. This study was conducted
covering two chapters from the text fidem Chemistry (Davics et al. 1999);
Chemical Equations and Reactions and Stoichiometry.

In the first section, Chemical Equations and Reactions, the major sub-sections
are describing chemical reactions, balancing chemical equations, classifying types
of reactions and using the activity series. In a chemical reaction, atoms are
rearranged to form new substances. Typical indicators that a chemical reaction
has taken place are a change in color, the formation of a gas or precipitate, and
the evolution or absorption of heat or light. When a chemical reaction occurs, mass
is conserved. The total mass as well as the numbers and typcs of atoms are the
same on both the reactant and product side of a reaction. Coefficients are used in
front of formulas in order to balance a reaction. An important component of
understanding chemical equations is to understand the symbols used therein.

Symbols are used in chemical equations to identify the physical statcs of

substances as well as the physical conditions during a reaction. For example, the
symbol (aq) stands for aqueous, which means the substance had been dissolved
in water. Chemical reactions are classified into five different types: synthesis,
decomposition, single replacement, double replacement, and combustion. In a
synthesis reaction two reactants form a single product. In a decomposition
reaction, a single reactant forms two or more products. In a single replacement
reaction, an element replaces an element from a compound. In a double
replacement reaction, the ions of two compounds switch places, replacing each
other and forming two new compounds. In a combustion reaction, a hydrocarbon
reacts with oxygen to form carbon dioxide and water. The activity series is a list of
elements ananged according to relative reactivity and is used to make predictions
about the products of a replacement reaction.

The second section of the study, Stoichiometry, deals with the quantities of
substanccs in chemical reactions. Balanced equations are used to compare the
relative amounts of substance, expressed as moles. Stoichiometry problems are
solved by using mole ratios from the balanced reaction as a conversion factor
between the two substances. In a chemical reaction, the limiting reactant is that
which is completely consumed in the reaction, thereby placing a limit on the
amount of product that is formed. The theoretical yield is me amount of product
that can be formed in a chemical reaction. The actual yield is the amount of
product that is collected when a reaction is actually carried out. The percentage

yield is the ratio of actual yield to theoretical yield multiplied by 100.

Theoretical Framework

Much research has been done in an effort to reveal the problems students
encounter in solving stoichiometry problems. Both Huddle (1996) and Smith (1978)
reported that the reason that many high school chemistry students encounter
difficulty in problem solving is because they do not have the capacity for formal
operational thought. Formal operational thought refers to the final stage of
cognitive development in a theory proposed by psychologist Jean Piaget. The
work of Piaget is well known by educators at all levels.

Piaget studied the cognitive development of children with the intent of teaming
how humans acquire knowledge (Bodner, 1986). Piaget’s theory of cognitive
development outlines four major stages: sensorimotor, preoperational, concrete
operations, and formal operations, along with an age range for each stage. The
stages commonly observed in the high school classroom are the final two stages,
concrete operations (7 — 11 years of age) and formal operations (12 — 15 years of
396)-

Concrete operations, which according Piaget’s theory appears between ages
seven and eleven, is characterized by a student being able to carry out logical
mental tasks tied to concrete objects or situations (Woofolk, 1998). In this stage,
students are able to use symbols to represent physical things, and are able to
manipulate these symbols, but only within the context of concrete situations. For
example, children at this stage can imagine what their bedroom would look like
with the furniture rearranged without actually moving the furniture (Woolfolk 1998).

They can create a drawing symbolizing their furniture and how it could be

arranged, but they can not do the same for pieces of furniture they have never
seen even when provided with the dimensions. Students are literally in a “hands-
on” thinking mode.

The final stage of cognitive development, formal operations, is reached
between twelve and fifteen years old. Ideally, in accordance with the age ranges of
Piaget’s theory of cognitive development, all eleventh and twelfth grade students
ages 16 to 18, such as those participating in this study, should be in this final stage
of cognitive development. Students capable of formal operational thought are able
to handle abstract thinking and reasoning. This is particulariy important in the study
of chemistry as much of it is unseen by the naked eye. Chemistry students do not
have the opportunity to see atoms or molecules and yet are required to perform
calculations involving the mole and Avogadro’s number. Reporting the number of
molecules at the end of a problem requires the use of formal operations as the
student is writing about something they have never seen, or touched. The key
characteristic of formal operational thought is hypothetico-deductive reasoning, a
problem solving strategy in which an individual identifies the factors affecting the
problem and then deduces and systematically evaluates solutions (Woolfolk,
1998). This method of thinking and reasoning is necessary in solving several types
of chemistry problems, including stoichiometry problems.

The sample stoichiometry problem in Figure 1 below asks the question directly
enough, but the onus is on the student to recognize that there are several steps
that need to be taken to arrive at the correct answer. The first step is to balance

the chemical equation. Arriving at the correct answer is impossible without this first

 

Sample Stoichiometry Problem:
As early as 1938, the use of NaOH was suggested as a means of

removing C02 from the cabin of a spacecraft according to the following
reaction:

NaOH + C02 —> Na2C03 + H20

If the average human body discharges 925.0 g of 002 per day, what mass
of NaOH is required each day for each person in the spacecraft?

 

 

(Davis et. al.)

 

Figure 1: Sample Problem

step; yet because the question does not overtly ask or tell the student to balance
the equation many, including students who have seen this type of problem before,
will skip the step altogether. This is an example of students failing to identify the
factors that affect a problem, which is a possible indicator of lack of formal
operational thought. Patricia Smith (1978), a high school chemistry teacher, noted
that, “At least half of the students are unable, not necessarily unwilling, to
understand such concepts as atomic structure, moles, polar and nonpolar bonds,
and the periodic law.”

Controversy has surrounded the age ranges associated with each stage of
cognitive development since the publication of Piaget's theory. However, most
important to the focus of this study is the controversy surrounding the final stage;
formal operations. Piaget's theory tells us that the stage of formal operations is
reached sometime between ages 12 and 15 and yetresearch hasshownthatthis
is not necessarily the case. Approximately 50% of high school students are unable
to use formal thought processes (Smith, 1978). High school teachers are not

alone in facing the challenges of teaching concrete operational students abstract

topics; college professors also identify these students in introductory courses
(Bodner, 1986). A study conducted in 1971 revealed that half of the college
freshman participating in the study had not reached formal operations. (Good
1979). In a summary of studies concerning Piaget’s cognitive levels, Ron Good
(1979) provides the following conclusion:
“Various studies indicate that from 25% to 75% of high school and college
students do not successfully use components of formal reasoning as (1)
using proportions, (2) making quantitative correlations, (3) making all possible
combinations, (4) controlling variables, etc.”
The formal thought processes listed by Good are key components in solving
stoichiometry problems with success, particularly using proportions. Mole ratios

are important proportions that are necessary to solve stoichiometry problems.

Even Piaget suggested that most adults may only be able to use formal-
operational thought in a few areas where they have the greatest experience or
interest (Woolfolk, 1998). It is therefore almost unreasonable to expect all students
in a general chemistry class in high school to all succeed in thinking hypothetically
about stoichiometry problems.

This does not mean that there are not students in the class capable of formal
operational thought. Formal operations students are indeed present and capable
of handling the task of solving stoichiometry problems. These students can also
benefit from the incorporation of concrete activities into their teaming almost as
much as their concrete counterparts. It is common for people at all levels of

cognitive development to revert to an eartier stage when confronted with a new

8

area of teaming (Bodner, 1986). When students arrive in General Chemistry at
Redford Union, none of them have heard of stoichiometry before and all of them
find the topic challenging if not difficult, formal Ieamers included. Therefore all

students should benefit from the incorporation of concrete learning experiences.

Piaget laid the groundwork for the constructivist model of teaming which is
neatly summarized by Bodner (1986) in a single sentence, “Knowledge is
constructed in the mind of the learner”. People do not discover knowledge, nor can
it be transplanted from the mind of the teacher into the mind of a student. Rather
knowledge is constructed as new information and models are incorporated into
existing knowledge structures (Woolfolk, 1998). People do this in order to make
sense of their experiences. When new knowledge is constructed it is then tested
in real world situations and if necessary, modified based on new experiences
(Bodner, 2001). An example of the testing of knowledge in physics is given by
Bodner (1986) below.

“The knowledge that a force must be applied to keep an object in motion is
viable in such commonplace experiences as driving a car; it ‘works’. When
faced with the task of making a relatively heavy dry-ice puck move at
constant speed across a smooth glass table, it is not surprising that students
try to achieve this goal by using a constant blast of air from an air hose. For
some students, it is only when they find that this does not work that they feel
obligated to revise their ‘knowledge’ to incorporate Newton’s laws. Once
developed, the, the knowledge contained in Newton’s laws is perfectly viable
for engineers and even most physicists. It is only when this knowledge is
tested in the domain of relativistic effects that it must be altered once more.”

In science classes, it makes sense that students develop their understanding
following the constructivist model. Students arrive in class with certain ideas and
misconceptions that they may modify as they acquire and test new knowledge. If
the student is responsible constructing new knowledge, then the student must be
active. Patricia Smith (1978) writes, “Both students hands and minds must be
actively involved for them to progress“. This is where teaching a topic such as
chemistry gets tricky. Sure, it’s simple enough to get hands-on learning done in the
laboratory, but how can the concepts of chemistry be taught in a hands-on manner

when the explanations exist on a molecular level?

The world that high school students live in is essentially macroscopic. They
deal with things that they can see; things that have mass that they can feel.
Unfortunately students do not realize that chemistry is also part of this world. They
cannot see the atoms or molecules undergo rearrangement during a chemical
reaction. Gabel (1999) writes, “In order to understand the microscopic [molecular]
level, a person must be capable of associating particles with models or analogies.”
The goal of the chemistry teacher then is to incorporate meaningful macroscopic

models into instruction.

Creating macroscopic models of molecular events makes use of visual-spatial
thinking. Matthewson (1999) defines visual-spatial thinking as follows, “Visual-
spatial thinking includes vision — using the eyes to identify, locate, and think about
objects and ourselves in the world, and imagery — the formation, inspection,
transformation and maintenance of images in the “mind’s eye” in the absence of a

visual stimulus.” The reanangement of atoms and molecules during a chemical

10

reaction lacks a visual stimulus for students; it is therefore necessary to give them
a model and images for their “mind’s eye”. Images are important in Ieaming in that
images carry a large amount of information. An image has the power to show
relationships between several ideas (Matthewson, 1999). Using a visual spatial
representation increases the power of the instruction by including the relationships
between items and not just a series of definitions linked together with even more
words. Students working with language without imagery are on a time deadline
when it comes to working memory as working memory serves as temporary

information storage only.

Woolfolk (1998) defines working memory as, the ‘workbench’ of the
memory system, the component of the memory where new information is held
temporarily.” The amount of working memory available is limited (Woolfolk, 1998).
Leaming chemistry can be very difficult because of the large number of unfamiliar
terms. Gabel (1999) writes, “If a word or chemical species is unfamiliar, it will take
up a much larger space in short-tenn memory than something familiar because of
an inordinate amount of time must be taken to make sense of it.” Woolfolk (1998)
supports this opinion, “Working memory... holds five to nine bits of information at a
time for 20 to 30 seconds.” Powerful images and visual spatial representations
can be processed within the 20-30 second time limit and cany the added meaning
of relationships between the items. Matthewson (1999) writes, “Teaching
strategies should foster a balance between the use of language and image by the

learner. “

11

One method for bringing the molecular world of chemistry and stoichiometry
into the macroscopic hands of teenaged students was developed by Liliana Haim ,
Eduardo Cortén, Santiago Kocmur, and Lydia Galagovsky, all of whom are
university instructors in Buenos Aires, Argentina. Their method uses the analogy of
fast food hamburger sandwiches to teach such concepts as chemical formulas,
balancing equations, mass conservation and limiting reactants. In this analogy, the
components of a hamburger sandwich symbolize atoms, which are the
components of molecules. Each component is assigned a mass value, just as
each type of atom has an atomic mass value on the periodic table. For example, a
slice of bread (B) is assigned a mass of 25 g and a hamburger patty (H) is
assigned a mass of 80 g. The formula for a hamburger is Bsz. From this
information students can calculate the mass of the hamburger and see that the
mathematical relationships between masses in chemistry is not inaccessible to
them, but merely logical. Students are then able to move to the next level, the law
of conservation of mass in a chemical reaction by using Haim’s reaction for
transforming HambChems (Bsz) and CheeseChems (82Ch2) into MacChems
(B3ChP2)I

2 Bsz '1' 2 BzChz 92 BaCI‘IPz 4" BzChz

By assigning mass values to each piece as above, students can calculate the
mass of sandwiches before the rearrangement, or reaction, equals the mass
afterward. This is a very simple example of the power of the analogy. Indeed, once
the groundwork is laid the analogy can carry through to understanding percent

yield. This hamburger analogy is excellent for teaching stoichiometry. Gabel (1999)

12

writes, “Novice chemists, whether at the elementary or college level, are familiar
with matter as ordinary objects that surround them. Taking this into consideration,
chemistry instruction should be based on the familiar macroscopic world.” The

hamburger analogy accomplishes this nicely.

The ability to understand the molecular concept of a chemical reaction as a
rearrangement of atoms is only the beginning of an understanding of
stoichiometry. Learning stoichiometry requires conceptualization skills as well as
mathematical and problem solving skills. The hamburger analogy allows students
to solve the problems by intuition (Haim, 2003). This demonstrates to the students
that there are simple mathematical procedures for solving stoichiometry problems,
procedures with which they are already familiar. Chemical reactions are similar to
kitchen recipes in many ways and because students are familiar with recipes and
the numerical relationships therein, it seems a good place to begin with numerical
relationship in stoichiometry. Haim, Umland, and Cain have all used recipes as a
model for stoichiometry with success in their classrooms. Umland (1984) writes,

“No one has any difficulty telling you that if a recipe says that it takes 2 ‘A
cups of flour and 2 eggs (plus other ingredients such as sugar, baking
powder, shortening, milk, and flavoring) to make 30 cupcakes and if you go to
the refrigerator and you find you only have one egg you can only make half a
recipe. You will need 1 1/8 cups of flour and will get 15 cupcakes.”

This demonstrates the concept as well as the mathematics of limiting reactant as
the chemical ingredient that will be used up first, thus limiting the amount of

product.

13

Linda Cain (1986) developed a demonstration that highlights the relationship
between recipes and stoichiometry. Cain’s demonstration makes use of the
traditional campfire treat, S’mores, to provide students with a concrete model for
Ieaming stoichiometry. The “recipe” Cain provides for making S’mores is as

follows:
ZGc+1M+3Cp-)1Sm

Where Gc represents graham crackers, M represents marshmallows, Cp
represents chocolate pieces and Sm represents S’mores. In this demonstration
simple, familiar macroscopic items are used to set-up a class discussion wherein a
number of useful questions can be asked; such as, “If we started with 10 graham
crackers, 5 marshmallows and 15 chocolate pieces, how many S’mores would we
get?” Students can see how the amount of reactant relates to the amount of
product and vice versa. Very quickly, the students realize that they already know
something of stoichiometry. Having activated their prior knowledge, the students
are ready to move on from the model and into the reality of chemical stoichiometry

and begin to deal with atoms and molecules.

One theory which promotes a connection between students Ieaming and
curriculum is the humanistic view. Woolfolk (1998) defines the humanistic view as
“An approach to motivation that emphasizes personal freedom, choice, self-
detennination, and striving for personal growth.” Bretz (2001) writes that
meaninng Ieaming takes place when students are provided with experiences that

require them to connect across three domains; cognitive, affective, and

14

psychomotor. The humanistic view uses the affective domain to help connect
abstract concepts. For example, students who learn about chemical reactions and
stoichiometry may be able to apply the knowledge to their lives in making choices
concerning recycling and feel empowered, activating the affective domain. The
cognitive domain is activated upon reading and thinking the concepts through
while the psychomotor domain can be activated through group activities or

laboratory work (Bretz, 2001 ).

In order to thoroughly understand stoichiometry, students must solve
quantitative problems. There are several methods with which this can be
accomplished, the most traditional of which is dimensional analysis. Dimensional
analysis is a problem-solving method that uses the fact that any number or
expression can be multiplied by a ratio equivalent to one without changing its
value. DePierro (2000) writes, “Dimensional analysis, ratio and proportion, and
plug-in type calculations may lead to correct numerical answers without a clear
picture of the associated physical situation and to the inability to write correct
equations.” He goes on to suggest that students struggle with problem solving in
chemistry because they do not understand the ratios used in dimensional analysis;
which follows logically from the suggestion that students may not be capable of
formal operational thought. Understanding and using proportions is a trait of hypo-
thetico deductive reasoning, the hallmark of formal operations. Patricia Smith has
heard from her students the same thing that l have heard from mine, “I can solve

the problem if you set it up” (Smith, 1978). This proves the point; students do not

15

understand the ratios being used, or why the ratios are being used, and thus are

unable to set up the problem themselves.

One method for enhancing student understanding of ratios used in dimensional
analysis is to use the think aloud strategy (DePierro, 2000). Gunning defines think
alouds as, procedures in which students are asked to describe the processes
they are using as they engage in reading or another cognitive activity.” Using a
think aloud forces students to articulate the meaning of the ratios, rather than just
knowing what ratio is to be used. When a student is able to describe the meaning
of a ratio in words, there is evidence of qualitative understanding which sets the
stage for success in quantitative problem solving (Depierro, 2000).

A natural setting for students to use the think-aloud strategy is in a cooperative
group setting. Cooperative Ieaming is simply students “...working together to
achieve common Ieaming goals.” (Herron, 1999) Students solving problems
together affords them a setting to articulate meaning verbally. Cooperative Ieaming
also “. .. encourages strong students to share their thoughts and Ieaming skills with
weaker students, and lets all students contribute to the team and experience the
strength of team Ieaming” (Bartholomew, 2006). Bartholomew suggests that a time
limit be placed on work done in cooperative groups, “... a short time helps focus
the students on the problem and may encourage groups to self-police team
members who do not seem to participate.” Chemistry students are most often
afforded cooperative Ieaming experiences in the laboratory. However, cooperative

learning groups or teams can also be effective in Ieaming problem solving.

16

Richard Felder uses group problem solving exercises in teaching stoichiometry
processes to chemical engineering students at North Carolina State University.
Felder writes, “Group problem solving exercises in class are an effective way to
teach material: they give active Ieamers something to do and reflective Ieamers a
chance to think” (Felder, 1990). It is important to engage students in any lesson,
but to engage students in a problem solving lesson can be particularty difficult.
Working in a group setting engages all students. Felder (1990) writes:
“Once students become involved they tend to stay that way, even after the
exercise is over, as little as five minutes of this type of activity spread over
the course of an hour can be enough to keep the whole class engaged for
the entire period.”

Students working in cooperative groups produces benefits in problem solving

exercises.

17

IMPLEMENTATION

This unit for teaching chemical reactions and stoichiometry was developed for
use in General Chemistry, an introductory chemistry course for students in 11th
and 12th grades. The prerequisite for general chemistry is a passing grade in the
9‘" grade science class, Geophysical Science. The unit covers two chapters from
the text Modern Chemist_ry (Davies et. al. 1999); Chemical Equations and
Reactions and Stoichiometry. The implementation of this unit began on the first
day that school resumed after winter break. The planned sequence is
summarized in Table 1 on page 19. Learning objectives were grouped into six
phases, which were to take approximately one week per phase to accomplish.
The order was chosen not only for logical progression, but to follow the textbook.
Following the text gives the student a device which supports their Ieaming and as
such it is easier for the learner when the instructor works with the text rather than
against it. Thus, the progression of lessons and acquired skills closely follows the
text.

Table 1 below lists the phases of instruction in the order in which they were
taught. Each phase included pieces of instmction used in previous years and
activities that were developed in order to give greater support to concrete
Ieamers. Activities that were developed or altered for use in this study are

denoted with an asterisk.

18

Table 1: Phases of Instruction

 

Phase 1

 

Objectives:

1. List three observations that a chemical reaction has taken place.
2. List three requirements for a correctly written equation.
3. Write a word equation and a formula equation for a given chemical reaction.

4. Balance a formula equation.

 

Instruction:

1. Chemical Reactions PowerPoint ®

2. Balancing Chemical Reactions
PowerPoint ®

3. Symbols Used in Chemical
Equations PowerPoint ®

 

Activities:

1. Burger Chem“
3. Formulas and Equations
b. Mass Conservation

2. Balancing Race“

3. Symbol stories"

 

Phase 2

 

Objectives:

1. Define and give general equations for synthesis, decomposition, single
replacement, and double replacement reactions.

2. Classify a reaction as synthesis, decomposition, single replacement, double
replacement or combustion.

3. Predict the products of simple reactions given the reactants.

 

Instruction: Activities:
1. Types of Reactions; Visualization 1. Lab: Types of Reactions“
with Stick Figures

 

 

Phase 3

 

Objectives:

1. Explain the significance of the activity series.

2. Use the activity series to predict whether a given reaction will occur and what
the products will be.

 

Instruction: Pctivities:
1. Activity Series PowerPoint® 1. Lab: Recycling Copper*

 

Phase 4

 

1. Define stoichiometry.
2. Write a mole ratio relating two substances in a chemical equation.

 

 

 

 

 

Instruction: Activities:
1. Introduction to Stoichiometry None
PowerPoint®
Phase 5
Objectives:

1. Calculate the amount in moles of a reactant or product from the amount in
moles of a different reactant or product.

2. Calculate the mass of a reactant or product from the amount in moles of a
different reactant or product.

3. Calculate the amount in moles of a reactant or product from the mass of a
different reactant or product.

 

19

 

Table 1 Continued

 

4. Calculate the mass of a reactant or product from the mass of a different

 

 

 

 

reactant or product.
Instruction: Activities:
1. Ideal Stoichiometric Calculations 1. S’more Lab“
PowerPoint® 2. Lab: Finding Stoichiometric
2. Modeling problem solving Coefficients
Phase 6
Objectives:

1. Describe a method for determining which of two reactants is a limiting reactant.

2. Calculate the amount in moles or mass in grams of a product, given the
amount in moles or masses in grams of two reactants, one of which is in
excess.

3. Distinguish between theoretical yield, actual yield, and percent yield.

4. Calculate percent yieldgiven the actuaneld and quantity of a reactant.

 

 

Instruction: Activities:
1. Limiting Reactant PowerPoint® 1. Burger Chem Yield and Limiting
Reactant
2. Lab: Percent Yield“

 

 

In addition to the activities listed above, each day students were given a
homework assignment that followed from the objectives covered in the lesson, in
accordance with the school policy which requires teachers to assign homework
each day. It is important to note that in addition to in-class activities, most students
also completed individual practice.

Phase One

The first lesson introduced the concept of chemical reactions including the
obligatory definitions and the law of conservation of mass. The information
presented was aligned with objectives 1-3 in Table 1 and presented via Microsoft®
PowerPoint® presentation. This lesson was simple and straightforward in order to
give students the vocabulary with which to discuss chemical reactions. The most

difficult component for the students was translating a word equation into a formula

20

 

equation as it is essentially Ieaming a new language wherein they have to know
the atomic composition of each compound in order to be successful.

The second lesson (Appendix A-l) utilized the hamburger analogy developed by
Haim. The premise for the analogy is that the principal of the school has a big
meeting and has ordered lunch from a local burger restaurant, “Burger Chem”.
Although the principal has ordered a specific number of a specific type of burgers,
the order is mixed up and the wrong sandwiches are delivered. Students must find
a way to make the changes to the sandwiches that were delivered in order to
provide the proper lunch for the principal’s meeting without the principal
discovering the error. Rather than simply make use of the analogy, Haim’s original
idea was extrapolated to create a concrete experience for high school students.
Using Crayola® Model Magic ® modeling compound, small models of components
of hamburger sandwiches were constructed. These components included bread,
hamburger patties, and cheese. These re-usable components of hamburger
sandwiches provided models for students to work with, employing visual-spatial
skills. The models were used in four different activities in the unit.

To begin the first “Burger Chem” lesson, students worked in groups of 2-3 and
the Formulas and Equations worksheet (Appendix A—l) was distributed along with a
set of hamburger model components. The instructions were for each group to build
models of the sandwiches following the given recipe, shown in Table 2.

21

Table 2: Burger Chem Recipes

 

 

 

 

Sandwich Bread (B) Cheese (Ch) Patties (P)
HambChem 2 0 2
CheeseChem 2 2 0
MacChem 3 1 2

 

 

 

 

 

 

Students were required to work on the problems in groups to solve the problem.
Students were provided 10 minutes to work together and then the class came
together as a group to discuss the answers. The rationale for a short time limit for
the group work was to reap the benefits described by Bartholomew; namely
promoting focus on the task and self—policing by the group to keep all members
involved. In order to have a purposeful class discussion following the group work
the Microsoft ® PowerPoint ® presentation included in Appendix A-l was used.
This lesson accomplished two tasks. First, it gave students the opportunity to carry
out logical mental tasks tied to concrete objects, bringing the abstract concept of a
chemical reaction to the concrete level through an analogy. This activity also
provided a macroscopic model for a chemical reaction. In the activity, students are
asked to write a reaction which symbolizes the transformation of sandwiches from
one type (HambChems) to another type (MacChems). Performing such a task fits
nicely into Gabel’s recommendation for understanding molecular events. Gabel
suggests that to understand molecular events, one must be able to associate the
event with a model.

Continuing on the same day with the “Burger Chem” activities, the class went

back to group work and completed the Mass Conservation worksheet (Appendix

22

A-ll). Again, instructions were for students to build the models and again the group
came together after 10 minutes to discuss the answers. In this activity students
were most struck by the fact that no components of hamburgers had been created
or destroyed in rearranging the pieces. When they were asked if they had the
same number of pieces that they had had at the beginning, they looked down at
their desks to check and found that mass had been conserved.

These two Burger Chem lessons gave students their first experience in
manipulating coefficients in a chemical equation while using concrete models.
Students were able to view a chemical reaction in the same light as they would
consider a recipe and understand that 100 B2H2 meant that there were 100
HambChem sandwiches. This set the stage for the next instructional piece,
balancing equations.

The next lesson provided direct instruction in balancing equations by
inspection. A Microsoft® PowerPoint® presentation was used for introduction.
Students were first provided a set of rules for balancing equations and then a
series of sample equations to balance. As the lesson progressed the teacher
gradually tapered support and allowed students to become increasingly active in
balancing the equations.

The following day students participated in a balancing race. To become an
expert at balancing equations requires a lot of practice by the student, but long
balancing assignments can be tedious and boring. In this activity students were in
competition with each other for various prizes held in high regard by high school

students. The prizes included such items as pencils, drink passes, one free tardy,

23

a homework pass and a hierarchy of extra credit points. Students that were
already capable of balancing equations had class time in which to practice and
those students who were not yet able to balance equations on their own were able
to get assistance from the teacher during this time. A copy of the equations race is
included in Appendix A-lll. The race was divided up into three sections of seven
equations each. At the end of each section, students were required to check in
with the teacher before proceeding to the next set of equations to get both
feedback and assistance if necessary. The balancing race occupied the first half of
a class period, at the end of which students had successfully balanced a total of
twenty-one equations.

The second half of the class period was devoted to understanding symbols
used in chemical equations. A Microsoft® PowerPoint® presentation was shown
(Appendix C-l). The homework assignment for the day was to write a story using
the symbols of chemistry in place of words. For example, NaCl (aq) is salt water
and it is fun to go swimming in NaCl (aq) with fins and a mask. The rubric used in
grading the stories in included in Appendix D. This activity concluded the first piece
of the unit.

Phase Two

To provide direct instruction in the five different types of chemical reactions, a
Microsoft® PowerPoint® presentation was shown. A grid was distributed for
students to record their notes. A blank student grid and a completed grid are
included in Appendix A-IV. The types of equations presented followed those in the

textbook; synthesis, decomposition, single replacement, double replacement, and

24

 

 

 

 

Oll

combustion. A macroscopic model was employed to enhance understanding. After
writing the equation type, definition and general equations, students drew stick-
figure representations for the reaction. In this model students are able to draw on
their experience about dating. A stick figure drawing representing a synthesis

reaction is shown in Figure 2.

 

gtjn‘tilé'SiB '.

 

 

 

 

Figure 2: Stick Figure Model
Students are asked if they have any friends that behaved completely differently

after acquiring a boyfriend or girifriend. The response is an emphatic, “Yes!” and
students understand that the same is true for the products in a reaction. While this
model is not quite as concrete as the burger analogy, it does provide a powerful
model for students to begin to understand reactions. The diagram provides an
image for the “mind’s eye” and creates a balance between language and imagery.
The lesson proceeded with stick figure models for all types of reactions. The idea
for utilizing stick figures to represent equations was borrowed from Tom Shalla, a
retired chemistry teacher from Harrison High School in Farmington Hills, Michigan.
Mr. Shalla taught reactions in this manner in 1987, and nearly twenty years later I
am able to remember the symbols and pass them along to my students.

The next day students went into the laboratory to perform one of each type of
reaction (Appendix B-l) The reactions performed are some that had been used

only as demonstrations in the previous years’ instruction and adapted to create a

25

laboratory experience for students. In completing each of the reactions students
had an opportunity to demonstrate mastery of a performance objective from the
first phase of the unit: to make observations that indicate that a chemical reaction
has taken place. At each station students were required to record their
observations, as well as write and balance the chemical equation.
At the synthesis station, students performed the following reaction:
2M9(s)+02(9)->2M90(s)
Student observations included a change in color as well as the significant amount
of heat and light produced in the reaction. As the decomposition station, students
removed water from a hydrate and observed a simple color change which they
reported to be quite uninteresting in the following reaction,
CuSO405H20(s) ——“—> CuSO4 + 5H20 (9)
At the single replacement station students performed a reaction in the fume hood
which involved the evolution of hydrogen gas through the equation
Zn (s) + HNOa (aq) -> Z"(N03)2 (aq) +H2 (9)
Students’ observations for the reaction included noting the formation of hydrogen
bubbles on the surface of the zinc. At this station they learned that the fume hood
removes dangerous gases and makes it safe for them to carry out reactions like
those above. At the next station students performed a double replacement
reaction with a spectacular color change. The reaction is as follows.
2 Kl (aq) + Pb(N03)2 (aq) -) Pblz (s) + 2 KN03 (aq)
The reactants are both colorless liquids, but the lead iodide precipitate that is

formed is a very bright yellow. The final type of reacfion was a combustion

26

reaction. Students particulariy enjoyed this station because they were able to
produce a small fire on a watch glass. The combustion reaction used is shown
below.

CHaoH (aq) + 02 (9)9002 (g) + 2 H20 (I)

The Types of Chemical Reactions laboratory experiment provided an
opportunity for students to understand that the symbols that they had been using in
class and in homework represented physical things, things that they handled in the
lab. This is an important task for the concrete operational learner.
$38.63:

The activity series of the elements is a list of elements arranged by relative
reactivity. An understanding of the activity series allows students to predict how
certain elements are able to replace others in single or double replacement
reactions. To introduce the topic a Microsoft® PowerPoint® presentation was used
(Appendix C-ll).

The following day students went to the laboratory to perform the Recycling
Copper Lab (Appendix B"). The pre-lab questions for this experiment reinforce
the objectives of phases 1 and 2, related to indications that a chemical reaction
has taken place and types of reactions. The experiment itself involves a series of
reactions which ultimately produce copper metal. Students are required to write
and balance the series of five reactions that take place in this experiment. All of the
reactions are carried out in one standard sized test tube. Students begin with
copper nitrate solution, and add sodium hydroxide:

Cu(N03)2 (aq) + 2 NaOH (aq) -) Cu(OH)2 (s) + H20 (I) + 2 NaNOa (aq)

27

Students recorded that they knew a reaction had taken place because of the
formation of a precipitate. The second reaction is the decomposition of the copper
hydroxide precipitate over heat to cupric oxide and steam following the equation
below.
Cu(OH)2(s) —A—-> CuO(s) + H20(g)
Again, it is easy to recognize that a reaction has taken place as the cupric oxide
formed is a black solid. Students noted the color change in their observations. The
third reaction put the copper back into solution through the following reaction.
CuO (5) + 2 HCI (aq) -) CuCl2(aq) + H20(l)
Students noted that a chemical reaction had taken place because the black cupric
oxide was consumed and the product was a colorless liquid. To produce copper
metal from the solution resulting from the reaction above, aluminum metal was
placed into the test tube resulting in the reaction below.
3 CuCl2(aq) + Al (s) -) 2 AICI3(aq) + 3 Cu(s)
For this reaction, students’ observations included the formation of the copper metal
precipitate. A reaction that takes place simultaneously with the one above is
6 HCI (aq) + 2 Al (5) -) 3 H; (g) + 2AlCl3 (aq)

Students noted the formation of bubbles for the above reaction. Post lab questions
required students to use the activity series of the elements to explain the
movements of copper within the framework of the 5 reactions carried out in this
experiment.

This laboratory activity allows for the activation of the cognitive, psychomotor

and affective domains. The ultimate question in the lab is, “Do you think that

28

peoplewhodesign metal recycling processesneedtokncwand usetheactivity
series? Why or why not?” This question provides a direct link into the daily lives of
students.Whentheychooseto recycleaproduct, oddsaregoodthatthereisa
chemical process that will take that product fiom being trash back to being useful.
In making the choice to recycle or not students experience empowerment. This
laboratory experiment connects the three cognitive domains, the most effective
combination for student Ieaming.

Upon completion of the objectives of phase three, students completed exit
surveys (Appendix D) for me first half of the study and a chapter test which was
not included in this study was administered as this marked the conclusion of a
chapter in the text book.
$9.825

This phase began by defining stoichiometry as a quantitative study of chemical
changes. The first day of instruction presented information in a Microsoft®
PowerPoint® presentation (Appendix C-lll). The main goal of this first day of
instruction was to quickly review calculations with moles and to introduce the mole
ratio as a conversion factor. This lesson attached additional meaning to the need
to balance a chemical reaction, an objective from phase one, and also lays the
groundwork for phase five, calculation of amounts of product from a chemical
reaction.

Film

The fifth phase of implementation involved mastery of quantitative relationships.

The first day provided further instruction via a Microsoft® PowerPoint®

29

presentation (Appendix C-IV) which included steps for problem solving as well as
several examples. The goal of the dais instruction was for students to be able to
solve simple stoichiometry problems involving mole to mole calculations and mass
to mass calculations.

The second day students were able to go into the lab and use the recipe for
S’mores to model the quantitative relationships in a chemical reaction. Linda Cain
(1986) developed a demonstration using S’mores to provide students with a
concrete model for understanding stoichiometry. In order to make the situation
even more meaningful for students, this demonstration was developed into a
laboratory activity. The recipe “reaction” utilized in the lab was nearly identical to
that used by Cain in her demonstration, the only difference being due to the size of
the chocolate pieces used to make the S’mores.

ZGc+Mm+2Cb-) S’m
where 60 is the symbol for graham cracker, Mm stands for marshmallow, Cb is the
symbol for a miniature chocolate bar, and S’m symbolizes a S’more. In the activity
students were able to verify the law of conservation of mass and then eat in the
lab, a very big treat indeed. In order to ensure the safety of the food, only one
Bunsen burner, which had been set aside for use with food, was used and wooden
skewers were used to roast the marshmallows. Used skewers were discarded
after the lab. Students certainly enjoyed the activity, but not all of them were able
to connect the recipe to the equation that governed the making of the S’more.

Several students required significant assistance in answering the post-lab

3O

questions which required calculations of amounts of a reactant or product given
the amount of a different reactant or product.

Because many students who struggled in completing the S’more Lab, the day
after the lab was dedicated to modeling good problem solving techniques for
simple stoichiometry problems. The lab gave them a firm footing in dealing with
amounts in a “recipe reaction” and prepared them to listen to how to handle a
chemical reaction. While the students were not successful overall in completing the
S’more Lab, the lab prepared them to listen and understand. The problem solving
lesson consisted of a series of problems from the book solved by the teacher,
while modeling the think-aloud strategy, and homework with similar problems was
assigned.

The final activity of this phase was a lab entitled Finding Stoichiometric
Coefficients, in which students carried out the following reaction:

Cu (8) + 2 A9N03 (aq) -> Cu(N03)2 (aq) + 2A9 (s)
At the start of the experiment, students weighed a piece of copper wire which
served as the solid copper for the reaction. The wire was placed in a test tube
containing 5 ml of 1 M silver nitrate solution, AgN03. From the information about
the silver nitrate solution, students were able to calculate the number of moles of
silver nitrate that reacted. After the reaction appeared to be complete students
carefully washed and dried the remaining copper wire and silver precipitate and
weighed each to determine how much copper had reacted and how much silver
had been produced. Armed with these data, students determined the mole ratios

for the three species measured and from there determined the stoichiometric

31

coefficients and wrote the balanced reaction. This lab experience was fabulous for
the students in that it took them outside of their comfort zone and forced them to
think like chemists. It was particularly distressing to some students that the mole
ratios obtained in the lab did not turn out to be perfect whole numbers as they had
been in problems in class. Nonetheless, overall students were successful in using
the mass-mole relationships to come up with the conect coefficients at the end of
the lab.

ME

The final phase dealt with determining the limiting reactant in a chemical
reaction and then calculating the amount of product, and finally determining
percentage yield for a reaction.

Following the routine of previous phases, the first day of instruction utilized a
Microsoft® PowerPoint® presentation (Appendix C-IV) which introduced the
vocabulary required for discussing limiting reactant and the steps for determining
which reactant is the one which limits the amount of product obtained in a reaction.
Percentage yield was also presented.

On the second day, the Burger Chem analogy was utilized to reinforce the
concepts of limiting reactant and percent yield. Following the same procedure as
the previous Burger Chem lesson, the Limiting Component worksheet (Appendix
A-V) was distributed and students were given 10 minutes to discuss the answers
in groups. The problem uses the same sandwiches as the previous Burger Chem
lessons, but this time asks how many MacChems, B3PZCh, can be made from a

delivery of 10 kg HambChems, 83H; and 10 kg CheeseChems, 82Ch2. In order to

32

answer the question, students must use a process identical to that required to
solve a limiting reactant problem, with HambChems as the limiting component. In
order to direct the class discussion of this problem a Microsoft® PowerPoint®
presentation (Appendix A-V) was used. V

The second half of this lesson focused on yield. In this problem 20 % of the
HambChems delivered were damaged by freshmen. Students discussed the
problem in small groups before coming together as a class to review the answers.
This time students had to use the stoichiometric coefficients and recognize the 1:1
relationship between HambChems and MacChems in order to arr'we at the conect
answer.

The final activity for this study was a lab experiment (Appendix B-IV) in which
students determined the percentage yield for a chemical reaction. The reaction
used in the experiment was one students are already familiar with, that of sodium
bicarbonate, NaH003, with acetic acid, HC2H3C02.

chHacoz (aq) + NaHCOa (s) -) NaCzH3C02(aq) + C02 (9) + H20(l)
In the pre-lab discussion, students are told that the acetic acid will be in excess
and that they are to use 0.05 moles of sodium bicarbonate to perform the reaction.
Students calculate the mass of sodium bicarbonate required and then carry out the
reaction in a pre-weighed 250 mL flask. The water produced in the reaction is
removed by heating the products to boiling on a hot plate. To determine the
amount of sodium acetate remaining in the flask, the flask is allowed to cool and
then weighed. Having carefully measured 0.05 moles of baking soda at the outset
of the experiment, students then expect to get m 0.05 moles of sodium

33

acetate at the end of the experiment. While none of the students measured a mass
of sodium acetate equivalent to 0.05 moles, the majority of students achieved a
percentage yield of 90% or greater.

The study was concluded with a review of the topics covered in the six phases
with the post-test to assess student Ieaming completed on the following day.

Assessments for the study included an introductory survey (Appendix D-l) given
on the first day of the study along with a pre-test (Appendix D-ll) to determine what
unit objectives, if any, had been mastered in previous science courses.
Throughout the implementation of the unit students wrote Weekly Reflections
(Appendix D-Vlll) each Friday which included a summary of the concepts studied
during the week, the process used to study those concepts, and the student’s
attitude about what they had teamed during the week. After the completion of the
first three phases of instruction, an exit survey (Appendix D-IV) was given in order
to gauge students’ perceptions about how successful they felt they were in
mastering the objectives. At the completion of phase six, a second exit survey was
given (Appendix D-V). At the conclusion of the study the post-test was
administered (Appendix DVD to determine what objectives student’s had
mastered during the instruction. Finally after the post-test students completed a
Test Self-Evaluation (Appendix D-VII) which allowed for the collection of anecdotal
data regarding test preparation and what the students felt they had teamed during

the unit.

RESULTS
Introductory Survey

At the beginning of the study an Introductory Survey (Appendix D-l) was given
in order to gain insight into students' goals and perceptions about what helps them
learn the most in a science class. The data is summarized in Table 3.

Table 3: Introductory Survey Data

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Plan to attend college or trade school 100 %
Plan to take chemistry in college 48 %
Plan to study science or medicine in college 71 %
Science is best subject 0 %

Typically has trouble in science 19 %
Math is best subject 48 %
Typical math grade is an A 52 %
Typical math grade is an B 58%

Always solve story problems 23 %
Usually solve story problems 61 %
Usually solve story problems with assistance 10 %
Rarely solve story problems 3 %

Learns most from lecture 32 %
Learns most from lab 23 %
Enjoys lecture most 3 %

Enjoys lab most 65 %
Enjoys homework least 32 %
In the lab: enjoys mixing chemicals most 58 %
In the lab: learns the most from making sense of results 52 %
In the lab: learns the least from writing own procedure 49 %

 

All of the students surveyed answered that they planned to go to college or
trade school after high school. 48% plan to take a chemistry class in college. This
suggests that less than half of the students surveyed actually wanted to be in the

class and learn chemistry. Yet 71 % answered that they would study science or

35

 

medicine in college. The numbers do not add up, if 71% plan to study science or
medicine, then 71% should plan to take chemistry in college. This appears to be a
misconception students have regarding college and careers. They assume their
future studies will be very narrow and in only one discipline when in reality the
requirements for a college degree include courses from outside the major area of
study and it is mandatory that in studying science, chemistry will be included and in
studying medicine, chemistry definitely will be included.

The majority of the students surveyed (52%) responded that a typical math
grade for them was an A and in science class the majority (58%) responded that a
typical grade was a B. 48 % chose math as their best subject and zero chose
science as their best subject. In fact, 19% chose science as the class with which
they typically have trouble. When considering story problems, such as those
commonly found in stoichiometry, 23 % responded that they always solve the
problem, 61 % responded that they can usually solve the problem, 10% could
solve the problem with help and 3% could rarely solve the problem.

In terms of methods of Ieaming, the majority of students felt that they learned
the most from lectures, with 32% choosing that mode as the most effective while
23 % responded that they learn the most from labs. As for what students like best,
only 3 % like lectures, and 65% like the labs best. Homework is the part of science
class that students like the least at 32%. Focusing specifically on lab work,
students most enjoy mixing the chemicals (58%) but feel that they learn the most

from making sense of the results of the lab. Nearly a majority of students (49%) felt

that they learned the least from writing their own procedures, which they had done
prior to this unit.
Etejest.

A pretest (Appendix D-ll) was given to students to assess prior knowledge.
Some of the content of this study is taught in ninth grade physical science and
therefore students should have some basic skills. In particular, Ninth grade
students receive instruction in indicators that a chemical reaction has taken place,
the law of conservation of mass, balancing equations, and types of chemical
reactions.

Of the 18 students participating in the study, three of them demonstrated prior
knowledge on the pretest as shown in Figure 3. Of those three, all were able to
classify a chemical reaction by type and one of the three was also able to balance
a chemical equation. The remaining 15 students were unable to answer any of the
10 questions correctly. Overall the prior knowledge of the group of participants was
low, as expected.

Post-Test

At the conclusion of the study a post-test was given that was identical to the pre-
test. The overall performance of the group was much better, a summary of the
data is below in Figure 3. The lowest score was 2 out of 10, a test that was left
mostly blank, and the highest score was 10 out of 10. Ironically the student who
scored 10 out of 10 wrote in her weekly reflections for the class that she had not
learned anything. Figure 3 below comoaring pre-test and post-test scores shows
that indeed she did learn something.

37

PrelPost Comparison

_ . t . a , _ ,4 .

6i ..... 4 - 4. 4 - . .

‘ DPreTest

. 7 A 7 b 7 7 7 lPostTest
4< a as 4 ~ , F . L , ’%V l
3 .4 4. .l - E .
2; - - - . - .. . . 4 - l
01 ‘7‘." l _ “ l- ’ ‘ l '- - ‘r l .

Number of Correct Resoponses
01
l

    

 

 

 

 

 

 

 

 

 

 

T l

‘ 123456789101112131415161718
Student#

7 Figure 3: Pre—testhost-test Comparison
Figure 4 summarizes the student responses for the post-test by item
number. Each item number corresponds to an objective of the unit. Most items
required the student to be successful multiple times. For example, item number 3
required students to balance 4 chemical reactions. The response was only

counted as correct if the student balanced all four equations correctly.

Response Comparison: Post Test

01

ch 20

o

2

0 15

g lCorrect
E 10 Ellncorrect
o

.8 ElBIank
E

3

z

0

Figure 4: Post-Test Response Comparison by Item Number

38

E_g_st-Test Item Analysis

Item 1 asked students to list the three requirements for a conectly written
chemical equation. Following instruction only 17 %, or 3 of the 18 students, could
correctly list all three. A response was counted as correct only if the student had all
three requirements. Responses with two of three correct were counted as
inconect. A plausible reason for this is that item 1 was the first objective presented
and after six weeks of studying reacfions and stoichiometry, students focused
much more on the quantitative aspects rather than on “simple” definitions such as
this.

Item 2 required students to classify 4 chemical reactions by type and 16 of the
18, or 89%, were able to get all 4 conect. This was the area in which students had
previous knowledge as was shown on the pre-test. ltern 3 consisted of balancing 4
chemical equations, and again 89% of students were successful. Item 4 asked
students to interpret the meaning of a chemical symbol, specifically the symbol
(aq) which means the aqueous, and once again 89% students were successful.

Item 5 asked students to use the activity series to predict whether a given
reaction would occur and what the products would be for four given reactions. Only
3 of the 18 participants, or 17%, completed the entire task successfully with correct
responses for all four reactions. An additional 5 students managed to write correct,
balanced equations for 3 of the 4 reactions, and 6 students wrote conect balanced
equations for 2 of the reactions. Errors included failure to properly use the activity
series, inconect formulas written for products, and incorrect balancing of the

reactions with the first two types of errors far outweighing the third. This was a

39

difficult, daunting item for students even though they had practiced a similar task in
homework. In a written Test Self-Evaluation (Appendix D-Vll) following the post-
test one student wrote that reading the beginning of a reaction, such as
Ni (s) + CuCl -)

they felt overwhelmed and gave up. Students had to decide first whether a
reaction would occur based on the activity series, then determine the products,
write the correct formulas for the products, and finally balance the reaction. It is
reasonable that students felt ovenivhelmed in that they needed to be conect in 4
steps in each of the 4 equations in order to be conect for this item.

Item six asked students to define stoichiometry and explain how chemists use
stoichiometry. 83% or 15 of the participants were able to do so successfully. One
of the students simply gave the definition of stoichiometry with no explanation of its
use, one student began to write an answer but failed to finish it, and one student
left the question blank. In fact, the student left the entire page blank.

In item seven, students were asked to describe a method for determining which
of two reactants is the limiting reactant. 12 students, or 67%, were able to conectly
describe a method for determining the limiting reactant. One student, rather than
answer the question asked, gave a rule of thumb and wrote, “The limiting reactant
is usually the heavier reactant.” The term “heavier” likely means the reactant with
the higher molar mass. Item 8 asked students to compare actual yield to
theoretical yield. 16 students, or 83 %, answered correctly, the two incorrect

responses were both left blank.

40

Item nine was a quantitative problem in which students were required to
determine the number of moles of product formed when given the mass of one of
the reactants for a double replacement reaction they had observed in the lab. 13
responses, or 78%, were correct with 2 students who left the question blank. Of
the incorrect responses, three students apparently did not refer to the balanced
equation and failed use the coefficients properly in mole ratios.

The final item was a quantitative problem in which students were to determine
the mass of reactant required to produce a given mass of product for a
decomposition reaction. There were 10 correct responses, 61%, and 2 blank. Of
the incorrect responses, 5 of them included only one error in calculating a molar
mass. These 5 students had correctly used the coefficients of the equation, but
made errors in calculating mass from the periodic table.

Exit Survefi

Two exit surveys were given during the unit. The first at the completion of
phase three and the second at the completion of page six. Each survey contained
two sections, the first dealt with Ieaming objectives and in the second section
students were asked to rank the classroom activities in terms of how helpful they
felt the activities were.

Table 4 below shows a summary of student responses for the first section of

exit survey 1.

41

Table 4: Summary of Skill Responses for Exit Survey 1
Describe how successfully you Rarely Some- Often Usually Always

 

 

 

 

can use these skills: times

Identify observations that a

chemical reaction has taken 0% 18% 4% 43% 36%
lace

Identify a correctly written .

chemical equation 7% 43% 25% 18% 7%

Wnte a word equation from a 11% 14% 29% 29% 18%

iven formula equation
Write a formula equation from a o 0
_given word equation 0 /o 11 /o 21 % 43% 25%

 

 

 

 

 

Balance a formula equation 0% 11% 21 % 25% 4%
Classify a chemical equation

according to its type 21% 29% 32% 18% 18%
Predict the products of simple

reactions given the reactants 21% 29% 21% 25% 4%
Use the activity series to predict

whether a reaction will occur and 14% 25% 25% 29% 7%
what the products will be

 

 

 

 

 

 

 

 

It is interesting that a total of 29% of students felt that they could always or
usually balance a chemical equation whereas the post-test data showed that
89% of students had mastered this skill. Students often underestimate their skills.
Only 36 % felt that they could always or usually classify a reaction according to
its type, yet on the post test 89% of students were able to do so. It is unlikely that
the students just managed to “get lucky” and guess correctly because for both of
these skills the post-test required 4 correct answers in order for the response to
be counted as correct.

When it comes to using the activity series to predict whether a reaction will
occur and what the products will be students’ perceptions about their abilities

were a little bit closer to reality. 36% responded that they could usually or always

42

r
r .
l
‘l
_

 

accomplish this task successfully and 17% had 4 correct responses for item 5 on

the post-test.

Table 5 shows student responses for the second section of exit survey 1.

Table 5: Summary of Activity Responses for Exit Survey 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

. . . . Not Some- Very

Descnbe how helpful these activrties were Helpful H‘g‘aftrl Helpful Helpful
P

PowerPoint® Presentations 0% 21 % 50% 29%
Burger Chem Lessons 4% 39% 39% 18%
Balancing Race 7% 32% 32% 29%
Symbol Stories 36% 36% 25% 4%
Types of Reactions Lab 4% 14% 50% 32%
Recycling Copper Lab 1 1% 21 % 36% 32%
In-Class Demonstrations 0% 14% 36% 50%
Reading the Text 29% 54% 18% 0%
Homework Papers 1 1% 29% 43% 18%

 

 

Students apparently found the majority of the instructional activities to be
helpful. There were not any activities that had a larger percentage of students
rank it as “not helpful” versus those that ranked it helpful. The least helpful items
were writing symbol stories and reading the text. The most helpful items were in-
class demonstrations and the lab activities.

The Burger Chem lessons were a worthwhile activity to use. One of the
students in the group suffers from attention deficit disorder and was very thankful
to have the opportunity to use the burger models in chemistry. During the study
she underwent therapy and changes in her mediation and when asked by the

doctor about school she mentioned the Burger Chem activities and how much

43

they had helped her in chemistry. I received a note from the counseling office
regarding this exchange and praising my efforts to keep this student engaged in
chemistry. A total of 57% of students ranked the Burger Chem activities as
helpful or very helpful. This, along with the high ranking of lab activities, indicates
that high school students do still require instruction about abstract concepts to
begin at the concrete level.

Table 6 shows student responses for the first section of exit survey 2.

Table 6: Summary of Skill Responses for Exit Survey 2

 

Describe how successfully you
can use these skills:

Rarely

Some-
times

Often

Usually

Always

 

Write a mole ratio relating two
substances in a chemical
equafion

0%

5%

5%

42%

47%

 

Calculate the amount in moles of
a reactant or product from the
amount in moles of a different
reactant or product.

0%

5%

16%

32%

47%

 

Calculate the mass of a reactant
or product from the amount in
moles of a different reactant or
product.

0%

11%

5%

42%

42%

 

Calculate the amount in moles of
a reactant or product from the
mass of a different reactant or
product.

0%

11%

16%

26%

47%

 

Calculate the mass of a reactant
or product from the mass of a
different reactant or product.

5%

5%

16%

32%

42%

 

Identify the limiting reactant in a
chemical reaction.

5%

5%

11%

53%

26%

 

Calculate the amount of product
(either mass or moles) in a
limiting reactant problem.

11%

16%

26%

32%

16%

 

Calculate percent yield, given the
actual yield and quantity of a
reactant.

 

 

0%

 

5%

 

5%

 

37%

 

53%

 

 

The data in Table 6 shows that students had more confidence in their abilities
in section 2 with fewer responses of “rarely”. A direct comparison to the post-test
can be made for calculating the amount in moles of a reactant or product from
the mass of a different reactant or product as that was they type of question
asked in item 9. Of the students surveyed, 74% responded usually or always for
making this type of calculation. On the post-test 78% were in fact able to do so.
This is the closest match of student’s perceptions to what they achieved on the
post-test.

Item ten on the post test asked students to calculate the amount of product in
moles in a limiting reactant problem. 61% of the participants were able to
complete the calculation without any errors. Only 48% felt that they could usually
or always complete such a calculation successfully.

Table 7 below shows a summary of student responses for the second section
of exit survey 2.

Table 7: Summary of Activity Responses for Exit Survey 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

32’3”“ how helpful these activities Hggrul 3%? Heipful ”Sign
Helpful
PowerPoint® Presentations 1 1% 5% 53% 32%
Burger Chem Lessons 1 1% 47% 32% 11%
S’mores Lab 1 1% 32% 32% 26%
Finding Stoichiometric Coefficients Lab 5% 26% 63% 5%
Percent Yield Lab 0% 32% 58% 1 1%
Problem Solving Modeling by Teacher 0% 11% 42% 47%
Reading the Text 53% 37% 11% 0%
Homework Papers 5% 16% 53% 26%

 

45

 

In this section students felt that the modeling of problem solving by the
teacher was most helpful to them with 89% ranking this as helpful or very helpful
whereas reading the text was least helpful, even less helpful than in the previous
section. This focus of the section was quantitative and it stands to reason that
reading about problem solving is less helpful than actually practicing it. Students
even felt that the homework was helpful to them in this section, ranking the
homework higher than the lab activities.

Two of the three lab activities were quite helpful to students with 68% ranking
them as helpful or very helpful. Students did not find the S’more lab to be as
helpful as the others. The S’more lab provided a simple model, based on a
recipe, for a chemical reaction. Perhaps the model was too simple. Students had
a difficult time answering the post-lab questions and making the connection
between the recipe they used in the lab and the reality of solving chemistry
problems. Overall, the students felt that the activities were helpful and aided

them in Ieaming about chemical reactions and stoichiometry.

DISCUSSION AND CONCLUSION

Overall, the data collected indicates that including concrete activities in a unit
about reactions and stoichiometry helps high school students to learn these
concepts well. In comparing the pre-test scores to the post-test scores, the
average improvement was 70% for the group. Although some students still
struggled to master the difficult content, several wrote in their Weekly Reflections
(Appendix D-Vll) for portfolios that the concrete activities, laboratory activities and
Burger Chem in particular, helped them to understand the molecular events that
take place during a chemical reaction.

The post-test required multiple successes, such as four conectly balanced
equations for that particular item to be counbd as a correct response. Students
could not just “get lucky”, they had to demonstrate mastery. Three students
achieved 9 out of 10 on the post-test. Two ofthose three had no conect responses
on the pre-test. One student achieved a perfect score on the post-test and yet
insists that she leamed nothing from the unit. The difference in the pre-test and
post-test scores was pointed out to her and she merely shmgged. An increase
from 10% to 100% indicates that she leamed something whether she is willing to
admit it or not. There is no question that she improved. The unit was successful;
the students that participated and did the work leamed stoichiometry and were
able to demonstrate the knowledge on the post-test.

The lowest grade on the post-test was 2 out of 10 and belonged to a student
who neither participated in class activities nor completed her homework. Despite
attempts to engage her and calls to her mother, her attitude did not change. She

47

did spend time after school for individual help, but failed to show any improvement.
This student reminded me of the students that Patricia Smith wrote about who say
“I can solve the problem if you set it up” (Smith, 1978). In our after-school
sessions, she would start her homework With my assistance, but she would never,
in this case it was literally never, follow through and finish her homework on her
own. The student did not accept responsibility in her role as a learner and there
was little that I could do to help her. This student was also a transfer from a
different state and arrived approximately one month before this unit was taught.
This put her at a disadvantage for the remainder of the year as students who had
been in the class all year had already learned how to read the periodic table, write
formulas and calculate the amounts of substances in moles. Without these
prerequisite skills, it was very difficult for this student. She commented on more
than one occasion that her old school did not teach chemistry at the same pace as
it is taught at Redford Union. However, I do not believe that the pace at Redford
Union is particularly fast. In speaking with chemistry teachers from other high
schools, most keep a similar or even faster pace.

The series of Burger Chem lessons, were successful. Table 5 shows that 57%
ranked the Burger Chem lessons as helpful or very helpful. Students enjoyed
using the burger models to build the sandwiches and were able to understand the
rearrangement of the burger components to form new sandwiches as a model for
a chemical reaction in the Formulas and Equations exercise. When I asked the
students if any components had been created or destroyed in the process of

rearranging the burger components they all looked down at their models before

48

answering. This event made it clear to me that students do in fact have difficulty
dealing with the abstract concept of a chemical reaction. They needed the
reassurance from the models before they were willing to give an answer. After they
looked and discovered that they still had exactly the same burger components, just
rearranged, one of the students said, “Oh!” That sound was enough to prove the
lesson worthwhile. Furthermore, the Burger Chem lessons provided cooperative
learning with problem solving. Students discussed the processes that they needed
to use in order to solve the problem The time limit for problem solving worked quite
well; all of the students were on task during the group work time.

Another activity that was particularly memorable to the students, according to
Weekly Reflections, was the visualization of chemical reactions with stick figures.
Even at the end of the year, months after the lesson, they remember that
decomposition is the equivalent of stick figure “divorce”. Unfortunately this lesson
was not included on the exit-survey and thus student perceptions can not be
quantified. However, student writings in portfolios included stick figures as a
highlight of the unit.

The most unpopular activity was the writing of Symbol Stories, with 36 % of
students ranking it not helpful (Table 5). This assignment required students to be
creativeandwriteastoryinwhichchemicalsymbolscouldbeusedinplaceof
words. While this assignment is wonderful from the standpoint of including writing
across the curriculum, students who are worried about understanding chemistry
felt that this creative assignment was a waste of time and energy and did not help
them to better understand the symbols used in chemistry. This is an assignment

49

that I will not likely use again based on the results of the exit survey data. Students
did not find the assignment helpful. I would rather spend time on items that they
felt were helpful to them in Ieaming reactions and stoichiometry.

All of the laboratory activities were successful in that the reactions occurred as
planned and there were no unforeseen difficulties. Students enjoyed the Types of
Reactions Lab in its simplicity as there was no quantitative data to be collected and
analyzed. This lab was adapted from a set of demonstrations that had been done
in previous years. Previously, rather than spend a day in the lab, demonstrations
were done to show each type of reaction. This year in order to increase the
interaction of students with the concepts they were learning, the demonstrations
were adapted to a lab format. I found that this was worth the time spent in the lab.
Students were able to write their own observations for each reaction and use the
information they had learned in class on that very subject. The ability to recognize
the physical changes that indicate that a chemical reaction has taken place was a
skill that the students needed for future labs. The types of reactions lab gave them
the opportunity to make those observations on their own rather than having them
pointed out by a teacher.

Less popular were the Recycling Copper Lab and the Finding Stoichiometric
Coefficients Lab. Table 5 shows that 11% of students ranked the Recycling
Copper Lab as not helpful. Table 7 shows that 5 % ranked the Finding
Stoichiometric Coefficients Lab as not helpful. Although less popular, the majority
of students felt that these labs were helpful. The Recycling Copper Lab required

the students to write five balanced chemical reactions when given the reactants

50

and the reaction type. Students who asked for help usually only required
assistance with the first reaction and once they understood the task, they were
able to complete the other four reactions.

In the Finding Coefficients Lab many students required assistance when
working to turn their calculated mole ratios into stoichiometric coefficients. This
step required the students to use their mathematical knowledge in order to scale
the numbers up and many were unable to do so without assistance from either
myself or other students. One lab group skipped using the mole ratios altogether
and simply wrote the balanced equation from their knowledge of the reaction,
rather than from data collected during the experiment.

The S'mores Lab originally written as a demonstration by Linda Cain (Cain
1986) and adapted into a laboratory activity to show the analogy between
stoichiometry and recipes. The idea was that students would realize that in using
recipes, they already know how to make stoichiometric calculations. While the
students enjoyed having S’mores for a snack, the questions they asked following
the lab showed that they were not easily able to make the connection between the
recipe and chemical reactions. Perhaps a pre-lab discussion which involves the
calculation of “moles of marshmallow would help students to understand where
the lab is going to take them. In the future pre—lab questions will be written to assist
students in getting ready to think about moles in the recipe analogy.

As I continue to teach chemistry I will incorporate concrete activities into the
cuniculum. As the saying goes, we have to play the hand we are dealt. In high
school General Chemistry there will always be concrete level students in the

51

course and it will always be my job to teach them to the best of my ability. This
study has proved to me that it is not that concrete students are unable to learn
stoichiometry, but that they require the special support of hands-on concrete
models as well as strong mental models in order to be able to handle the level of

abstraction in chemistry.

52

Appendix A

Classroom Activities

53

Appendix A-l

Burger Chem Formulas 8. Equations

 

Mrs. Scott is having a meeting of the Mega-League Principals and has asked you
to order lunch from a hamburger chain called Burger Chem that makes
sandwiches using two or three identical slices of bread. You ordered 100
MacChem sandwiches, but somebody made a mistake and 100 HambChem and
100 CheeseChem were delivered instead. You need to convert these other types
of sandwiches into 100 MacChem before Mrs. Scott notices the error.

How many HambChem and CheeseChem do you need to obtain 100
MacChem sandwiches if compositions are:

 

Sandwich Bread Cheese Patties
(3) 10h) (P)

 

 

 

 

HambChem 2 0 2
CheeseChem 2 2 0
MacChem 3 1 2

 

 

 

 

 

 

 

Try to think about this as a cook/chemist. A cook uses a recipe, a chemist uses a
formula.

1. Write formulas for each of the sandwiches listed in the table above.

HambChem:

 

CheeseChem:

 

MacChem:

 

2. Write the formulas for the reactants (stuff you’re putting in).

3- Write the formula for the product (stuff you’ll get at the end).

Appendix A-I

4. Write an equation that represents the change in sandwiches that is to occur.

5. Using the equation you wrote in number 4; use coefficients to represent the
amounts of sandwiches. Balance the equation you wrote — make sure each
side had the same amount of bread, same amount of cheese, same amount
of patties.

55

Appendix A-l

 

Burger Chem:
Formulas and Equations Presentation

 

The Problem @

 

 

The Mega League Principals
Meeting is expecting lunch in
the RU Library.

We ordered 100 MacChems
but 100 HambChem and 100
CheeseChems were
delivered.

Oh no!

We need to fix this before
those principals finds out!

 

 

 

What We Know

 

. We have 100 HambChems and 100
CheeseChems.

- We need 100 MacChems.

 

 

 

 

 

Sandwich Bread Cheese Patties
(B) (Ch) (P)
HambChem 2 0 2
CheeseChem 2 2 O
MacChem 3 1 2

 

 

 

 

Let’s simplify this by writing sandwich formulas.

 

56

 

 

Appendix A-l

 

Let’s Write a Burger Equation

 

 

0 We have 100 HambChems (szz) and 100
CheeseChems (BzCh2.)

- We need 100 MacChems (B3PZCh) .

Reactants -) Products
(what we have) -> (what we get)

l32l32 + BzChz —> B3P2Ch + leftovers?

 

What about coefficients?

 

 

 

IZP2 + B2Ch2 -) B3P2Ch + leftovers

- We have 100 HambChems (B2P2) and 100
CheeseChems (B2Ch2.)

- We need 100 MacChems (B3P2Ch) .

100 BZP2 + 100 BZCh2 -) 100 B3P2Ch + leftovers

 

57

 

Appendix A-I

 

Predict the leftovers

l
A

100 B2P2 + 100 BzChz —> 100 B3P2Ch + leftovers

400 B 300
200 p 200
200 C h 1 00

At the end we will have 100 B, 0 P and 100 Ch.
We can make CheeseChems with that!

How many can we make?

 

 

Predict the leftovers

 

 

100 B2P2+ 100 BzChz —) 100 B3P2Ch +50 B2Ch2
400 B 36 400
200 P 200
200 Ch 136 200

Q With 100 B, 0 P and 100 Ch, how
many BZCh2 can we make?

' ,4 x 50

 

58

 

Appendix A-l

 

Questions to Answer

 

 

 

- What does a chemical formula
tell you?

 

- What does a chemical equation
tell you?

 

59

 

Appendix A-Il
Burger Chem Mass Conservation

 

According to your textbook, what is the law of conservation of mass?

 

 

Use the data below to answer the questions that follow.

 

 

 

 

Item Symbol Mass
Bread B 25 g
Patty P 80 9
Cheese Ch 15 g

 

 

 

 

 

1. What is the mass of 100 MacChem (33P2Ch) sandwiches?

2. Is there any relationship between the mass of 100 MacChem (83P2Ch)
sandwiches and the masses of 100 HambChem (B3P2) plus 50 CheeseChem
(BZChz)?

If so, what is it?
If not, why not?

3. State the law of conservation of mass in your own words.

60

Appendix A-ll

 

Burger Chem:
Mass Conservation Presentation

Mass Relationships

 

- What is the mass of 100 MacChem

 

 

 

(B3P2Ch) sandwiches?
Item Symbol Mass
Bread B 25 g
Patty P 80 g

 

 

 

 

 

 

Cheese Ch 15 g

 

(Subscript) x (Item Mass) = Total Item Mass

Sum of Total Items = Mass of Sandwich

 

Mass Relationships

 

- Let’s find the mass of one MacChem
(BBPZCh) sandwich first.

Bread Mass: 3 x 259 = 759

Patty Mass: 2x 809 -= 1609
Cheese Mass: 1x159 = 159

B3P2Ch Mass: = 2509

The mass of 100 MacChems would be: 2500 g or 2.5 kg

 

61

 

Appendix A-ll

 

Mass Relationships

 

- Is there a relationship between the mass of
100 MacChems and the masses of 100
HambChems plus 50 CheeseChems? EBB

’c‘»

Of Course! —-v

I

100 B2P2 + 100 BZChZ —> 100 33PZCh + 50 32Ch2

Mass in equals mass out.

Atoms in equals atoms out.

 

Questions to Answer

 

 

 

. What does a chemical formula
tell you?

 

- What does a chemical equation
tell you?

 

62

 

Appendix A-Ill
RACE: Balancing Chemical Equations

 

Balance the equations below showing all work. Each time you
complete a section, bring it up to be checked before proceeding to
the next section.

 

 

 

 

 

Balance with care.
2. KCIOg 9 KCI + 02
3. NaCl + F2 9 NaF + Cl2
4. H2 + 02 9 H20
5. Pb(OH)2 + HCI -) H20 + PbClz
6. AlBl’a + K2804 9 KBT + Al2(304)3
7. CH4 + 02 9 CO2 + H20

 

End of Section 1: Time to Check-In

 

 

 

63

Appendix A-lll
8. C3H8 + 02 9 002 + H20

9. CaH13 + 02 9 CO2 + H20

10. FeCl3 + NaOH -) Fe(OH)3 + NaCl

11. P+ 029 P205

12. Na 4' H20 9 NaOH + H2

 

14. $3 +

 

 

 

End of Section 2: Time to Check-In

 

 

 

64

15.

16.

17.

18.

19.

20.

21.

Appendix A-Ill

C02 + __ H20 9 CsH1205 + _02

 

K + MgBrz 9 KBr + Mg

HCI + CaCO3 9 CaCIz + H20 + C02

HN03 + NaHC03 9 NaNO3 4' H20 + C02

H20 + 02 9 H202

NaBr + Can 9 NaF + CaBrz

H2804 + NaNOz 9 HN02 + Na2$O4

 

End of Section 3: Time to Check-In

 

 

 

65

Appendix A-IV

 

 

 

 

 

 

acteucem cans:

 

coaaaam .2230

 

cease—on—

 

on»...

 

 

ecozeuem 3252.0 ho «on»...

 

 

Appendix A-IV

 

.329 85265

of + «00 A. s.0+ v.16

seam; new c266 .693
96% 9m 20:86 one
cum:

ucm Em: 8:85 2 comes
5? 2588 209893:

5:95:80

 

we... we.

m0 + O<Aloo + m<

6.6:th gamma: age

32 9338 mi. .wucaanoo
305 E 550 some

comic. mucaanoo accept?
Ea: mEofi Emcee—Eu ccc>>

EcEeomaem
03:00

 

fielme

m+0<AlOm+<

.ucaanoo m co :3
mm EcEQe 550cm weenie.
EcEQm “38388:: cm :23

EmEoomacm
seem

 

Balm.

m+<Arm<

.mcocfimnam LeEEfi
99: Lo 92 25 Esau exams
3:933 .8388 m cec>>

coEmanooco

 

slaw

m<Alm+<

.eocflmnsm
6358 92: .26:

m 8.2 2 2388 $2933
29:6 90.: .o N ccc>>

c.3556

 

unto—E3. 9.5.2

 

noses—cm .2280

 

eeaeeen

 

2.3.

 

 

ecozueem 3982.0 ho meet.

 

 

67

Appendix A-V
Burger Chem Limiting Component

 

In an earlier exercise, Formulas and Equations, you were asked to make 100
MacChem sandwiches from a delivery of 100 HambChem and 100 CheeseChem
sandwiches.

lm ortant information:

 

 

 

 

 

 

 

 

 

Item Symbol Mass Sandwich Formula
Bread B 25 g HambChem B3P2
Patty P 80 g CheeseChem 82Ch2
Cheese Ch 15 g MacChem B3P2Ch

 

 

 

 

 

 

 

 

1. How many MacChem sandwiches could be made from a delivery of 10 kg
HambChem and 10 Kg CheeseChem sandwiches?

2. Why did you eventually have to stop making MacChem sandwiches?

3. What sandwich determined the total number of MacChem sandwiches that
could be made?

4. What have you Ieamed about the limiting component in a chemical reaction?

68

Appendix A-V

 

Burger Chem:
LimitingComponent Presentation

 

Limiting Component

 

 

- How many MacChems (B3P2Ch) could be
made from 10 kg HambChem (B3H2)and 10
kg CheeseChem (BZChZ)?

 

Item

Symbol

 

Bread

B

259

 

Patty

P

809

 

 

Cheese

 

Ch

 

159

 

 

 

Let’s figure out how many HambChems &
CheeseChems we actually have.

 

Limiting Component

 

 

 

What is the mass of a HambChem? 235 9
What is the mass of a CheeseChem? 80 Q
What is the mass of a MacChem? 250 g

 

How many HambChems are in 10 kg?

1% :50: = 42.6 HambChems = 42 HambChems

How many CheeseChems are in 10 kg?

10830: = 125 CheeseChems =125 CheeseChms

 

69

 

Appendix A-V

 

Limiting Component

 

 

- We have 42 HambChems and 125
CheeseChems. How many MacChems
can we make? 42

42 B2P2 + 125 B2Ch2 9 B3P2Ch + BZCh2

What component will we run out of first?
The patties.
There are 2 pattles In a HambChem and 2 In a MacChem.
When we run out of HambChems, we're done.

 

Questions to Answer

 

 

 

- Why did we have to stop
making MacChems?

- What sandwich determined the
number of MacChems that
could be made?

 

- What did you learn about the
limiting component?

 

70

 

Appendix A-Vl

Burger Chem Yield

 

In an earlier exercise, Formulas and Equations, you were asked to make 100
MacChem sandwiches from a delivery of 100 HambChem and 100 CheeseChem
sandwiches. This time your job is further complicated by damage to some of the
sandwiches. 20% of the HambChems were ruined during the assembling of the
MacChems.

 

Sandwich Formula

 

HambChem 33P2

 

 

CheeseChem B2Ch2

 

MacChem B3P2Ch

 

 

 

 

1. How many MacChems can you produce?

2. How has the destruction of 20 % of the HambChems affected the efficiency of
the whole process?

3. How does the limiting component in a chemical reaction effect the efficiency
(or yield) of the reaction?

71

Appendix A-VI

 

Burger Chem:
Yield Presentation

Yield

W i

- Theoretical Yield: The calculated amount
of product you expect to get in an
experiment

- Actual Yield: The amount of product you
actually get (measured amount).

- Percent Yield:

 

% yield actual yieldx1000/
=————— 0
theo. yield

 

 

@ The Problem @
‘1

- The Mega League Principals
Meeting is expecting lunch in
the RU Library.

We ordered 100 MacChems
but 100 HambChem and 100
CheeseChems were
delivered.

Oh no!

We need to fix this before
those principals finds out!

 

 

 

 

72

 

Appendix A-Vl

 

@ Delegating work...
f

- Being very busy, you grab a
group of reliable looking
freshmen.

- You set them to work
rearranging the sandwiches.

o This crack squad of sawy
kids damages 20% of the
HambChems.

- How many MacChems can
you produce now?

 

 

 

 

Recall Our Burger Equation
l 4]
0 We had 100 HambChems (szz) and 100
CheeseChems (BZCh2.)

- We need 100 MacChems (B3PZCh) .

100 B2P2 + 100 l320h2 -> 100 B3P2Ch + 50 razor:2

The freshmen destroyed 20% our HambChems.
We have 80 left.

Now what?

 

73

 

Appendix A-VI

 

Recall Our Burger Equation

 

100 B2P2 + 100 B2Ch2 -> 100 B3PZCh + 50 BZChz

From our equation we know that if we have 100
HambChems we can make 100 MacChems.

With 80 HambChems. we can make 80 MacChems.

This is a one to one relationship; the coefficients are
the same.

 

 

Questions to Answer

 

l

- How has the destruction of 20%
of the HambChems affected the
efficiency of the whole process?

 

- How does the limiting
component in a chemical
reaction effect the efficiency (or
yield) of the reaction.

 

74

 

Appendix B
Laboratory Experiences

75

Appendix B-l

Types of Chemical Reactions

 

In this lab you will be investigating the four types of reactions that we studied in
class. Each lab station will take 10-15 minutes. If you finish before time is called,
use the extra moments to answer questions at the end of each station. Each
station will support more than one pair of experimenters; share nicely. It is
important to wear goggles at every station, even if you are answering questions.
Chemicals are in use around you and you have only one set of eyes.

Purpose:
To gain an understanding of the five types of reactions by performing each type
as well as writing an equation for each type.

Materials:
Materials for this lab are organized by station. At each station, goggles are
required.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[ Station 1 7i Station 2 |[ Station 3 ]| Station 4 If Station 5 ]
Magnesium Colpperm) 1 piece of 0.25 M. Ethanol
Ribbon su ate mossy zinc potassrum

pentahydrate lodlde

0.125 M pipet

Bunsen . 10 mL

Ring stand lead
Burner beaker nitrate

. . watch watch

Tongs Clay triangle pipet _gl a s 8 Ease

Bunsen 5 M nitric waste 1 match

burner acid beaker

forceps gloves pipet

crucible

Waste

beaker

Procedures:

S_tation 1 : Synthesis Reaction

At this station, you will observe the reaction of magnesium metal with
atmospheric oxygen to form magnesium oxide. This reaction gives off a great
deal of light and heat.

1. Obtain a small piece of magnesium ribbon (about 5 cm in length).

76

Appendix B-l

Light a Bunsen burner and adjust it so that the blue cone of the flame is
clearly visible.

Using your crucible tongs, hold the magnesium ribbon directly over the blue
cone of the flame until the reaction starts.

Record your observations.

When the reaction is finished, clean up your lab station by sweeping the
magnesium oxide residue into the trash.

Station 2: Decommsition Reaction

At this station you will decompose copper (ll) sulfate pentahydrate into copper (ll)
sulfate anhydrate and water.

1.

2.

Set up a ring stand with a ring, clay triangle, and Bunsen burner.

Use forceps to place a crystal of copper (II) sulfate pentahydrate into a
crucible. Use your crucible tongs to place the crucible in the clay triangle.

Light the Bunsen burner and heat the crucible for five minutes.
Record your observations.
When the crystal no longer appears to be changing color, turn off the Bunsen

burner and let the crucible cool for five minutes. The copper (II) sulfate
anhydrate Should be placed into the labeled waste beaker for recycling.

Station 3: Siggle Replacement Reaction

At this station you will be observing the reaction between metal zinc and nitric
acid, HNO3 to form hydrogen gas and zinc nitrate.

1.

2.

 

In the fume hood, place a piece of mossy zinc into the 10 mL beaker.

Put on a pair of rubber gloves before handling the nitric acid.

Nitric acid is corrosive! Wear safety goggles. Avoid contact
with skin and eyes. Avoid breathing vapors. If you spill some

on you immediately flush the area with water and notify your
teacher.

77

Appendix B—l
Fill a pipet with 5 M nitric acid and squeeze it into the 10 mL beaker.
Record your observations.

When the reaction has stopped, carefully pour the contents of the 10 mL
beaker into the waste beaker containing sodium bicarbonate. This will
neutralize the remaining nitric acid. Wipe the countertop in the fume hood with
a paper towel to ensure that no nitric acid droplets remain.

Station 4: Double Replacement Reaction

The reaction you will be observing is the reaction of lead (ll) nitrate and
potassium iodide to from dissolved potassium nitrate and lead (II) iodide
precipitate. This reaction was once used in the manufacture of paint for
household products. This reaction is no longer used due to the toxicity of lead.

1.

In a watch glass, place drops of 0.25 M potassium iodide solution using the
labeled pipet.

To this watch glass, add 5 drops of 0.125 M lead (II) nitrate solution using the
labeled pipet.

Record your observations.

Rinse the precipitate into the labeled waste beaker.

Station 5: Combustion Reaction

At this station, you will observe the combustion of ethanol, CZHSO, a common
gasoline additive.

1.

2.

Place about 10 drops of ethanol into a watch glass with a pipet.

Light and drop a match into the ethanol, making sure not to put your hand too
close to the flame.

Record your observations.

Once it has cooled, throw the match into the trash.

78

Appendix B-l

Observations:

 

Station Observations

 

 

 

 

 

 

 

 

 

Analysis:
1. Station 1 Question: Write the chemical equation for the synthesis of
magnesium oxide from magnesium and oxygen.

79

Appendix B-l

. Station 2 question: Write the equation for the decomposition of copper (ll)
sulfate pentahydrate into copper (ll) sulfate anhydrate and water.

. Station 3 questions:
a. Write the equation for the reaction you observed.

b. What do you think the bubbles were that you saw being formed?

. Station 4 questions:

a. The precipitate you formed, lead (ll) iodide, was once used as a pigment
in paint for a common school product. What do you think used to be
covered with this paint? Why?

b. Why do two clear solutions form a colored compound when they are
combined? After all, when you mix water with rubbing alcohol, the
resulting solution is colorless.

0. Write the equation for the reaction you observed at station 4.

80

Appendix B-l

5. Station 5 questions:

a. Ethanol fires are far less hot than gasoline fires. This makes them safer to
use in automobiles, but less capable of producing large amounts of
energy. Keeping this in mind, do you think that ethanol is a good source of
fuel for automobiles? Explain.

b. Write the equation for the combustion of ethanol.

81

Appendix B-ll

Recycling Copper

 

Background:

We can make a good new use of materials at the end of their
natural life by recycling them. The material from the old object is
reprocessed to make new things. Many recycled products
undergo chemical processes to reclaim the material that is
valuable. In this lab you will begin with a copper solution and end
with copper metal which we will wash, dry and weigh to determine
the amount of copper produced.

 

€79

Pre-Iab Questions:
1. Write the chemical formulas for the following:

a. copper (ll) nitrate

 

b. hydrochloric acid

 

0. sodium hydroxide
2. List four indicators that a chemical change has taken place.

 

3. List and give the general equations for the four types of chemical reactions.

 

Reaction Type General Equation

 

 

 

 

 

 

 

 

4. Explain the Significance of the activity series. Can predictions be made about
what will occur between two reactants based on the activity series?

82

Appendix B-ll

Purpose: To put reaction writing and balancing Skills to work in the recycling

of copper.

Materials: 1.0 M copper (ll) nitrate ring stand ruler

1.0 M hydrochloric acid wire gauze goggles
1.0 M sodium hydroxide stirring rod lab marker
100 mL beaker Bunsen burner filter paper
50 mL beaker test tube filter

12 cm aluminum wire distilled water

Procedure:

1.

Place 50 mL of water in a 100 mL beaker and heat it. This will be the hot
water bath used in step 5.

. Use the lab marker to make 3 marks on the test tube that are 1 cm apart.

Make the marks starting at the bottom of the test tube and moving toward the
top. Measure accurately to insure that the proper volumes are marked.

. Carefully place 1.0 M copper (ll) nitrate to the first mark on the test tube.

. Add 1.0 M sodium hydroxide up to the second mark on the test tube.

Sodium hydroxide is corrosive. Be certain to wear safety goggles
‘ ' and avoid contact with skin and eyes. If you spill some on you
immediately flush the area with water and notify your teacher.

Mix the solutions with the stirring rod. Rinse the stirring rod with water, then
touch the outside of the test tube to see if heat has been released. Record
your observations for reaction A.

. Put the test tube into the water bath prepared in step 1. Heat it until no more

changes occur. Record your observations for reaction B.

. Remove the test tube from the hot water bath. Turn off the burner. Cool the

test tube and its contents for 2 min in room temperature water. Add 1.0 M
hydrochloric acid to the third mark on the test tube.

Hydrochloric acid is conceive. Be certain to wear safety
goggles and avoid contact with skin and eyes. Avoid breathing
vapors. If you spill some on you immediately flush the area with
water and notify your teacher.

 

Mix with the stirring rod then rinse the stirring rod with water. Record your
observations for reaction C.

83

Appendix B-ll

7. Place a 12 cm piece of aluminum wire in the test tube. Leave it until no further
reaction is observed. Touch the bottom of the test tube to check for any heat
changes. Two reactions are taking place Simultaneously in this step. Record
your observations for reactions D & E.

8. Clean all glassware that you have used and your lab station. Return
equipment to its proper place. Dispose of chemicals in the containers
designated by your teacher. Do not pour any chemicals down the drain or in
the trash. Wash your hands thoroughly before you leave the lab and after all
work is finished.

Observations:

Reaction Observations

 

 

 

 

 

D&E

 

 

 

 

Appendix B"

Analysis:

1. Reaction A was a double replacement reaction. The reactants were copper
(ll) nitrate and sodium hydroxide. Use the activity series to write the complete
balanced reaction below.

2. Reaction B involved the decomposition of the copper product of Reaction A.
Refer to page 260 (Decomposition of Metal Hydroxides) of your textbook as
well as the activity series to write the complete balanced reaction below.

3. Reaction C was a double replacement reaction between copper (ll) oxide and
hydrochloric acid. Use the activity series to write the complete balanced
reaction below.

4. Reaction D was a single replacement reaction between the copper containing
product of reaction C and aluminum. Use the activity series to write the
complete balanced reaction below.

5. Reaction E involved the evolution of hydrogen gas. Use the activity series to
write the complete balanced reaction below.

85

Appendix B-ll

6. The chemical conversion of one product into another useful product iS the
basis for recycling. Explain how the type of reactions you observed in this
experiment could be useful in the recycling of copper.

7. Do you think that people who design metal recycling processes need to know
and use the activity series? Why or why not?

86

Appendix B-Ill

S’more Lab

 

Background:
S’mores are treats that campers enjoy making over a fire. The recipe for making
a S’more is ‘

2 Go + Mm + ZCb—>S'more
Just as a recipe tells you the amounts of ingredients you need, a chemical
reaction tells you the amount of reactant needed to get a certain amount of
product.

Purpose: To learn what stoichiometry is while using a Simple recipe.

Materials: Graham crackers (Gc)
Marshmallows (Mm)
Mini Chocolate Bar (Cb)
Balance

Procedure:
1. Study the balanced reaction for making a S’more.

2. Gather the materials you need and record the mass of the reactants. Then
add up the masses of all of the reactants to find the total mass of the
reactants.

 

Mass of 1 Go

Mass of 2 Go

Mass of Mm

Mass of 2 Cb

Total Mass of Reactants

 

 

 

 

 

 

 

 

3. Assemble your S’more then record the mass of the product.

 

Mass of S’more
Total Mass of Products

 

 

 

 

 

4. Do NOT eat your S’more until you have answered the Analysis questions.

87

Appendix B-III

Analysis:
Use the balanced equation from step 1 and your data to answer the following
questions:

1. Does the total mass of reactants equal the total mass of the products? Use
your data to support your answer.

2. Should the total mass of reactants equal the total mass of the products? Why
or why not?

3. What law have you just verified?

Now you can eat the S’more.

Solve problems 4- 6 by using the masses that you obtained in your data table aS
if they were molar masses taken from the periodic table of S’more ingredients.

4. How many “moles” of Mm are present in 5.0 g of Mm?

5. What mass of Go would be needed to react with 5.0 g of Mm?

88

Appendix B-Ill

6. What maSS of S’moreS could you make using 15.0 g of Go and excess Mm
and Cb?

This is stoichiometry! Stoichiometry is the relationship between the masses and
quantities of reactants and products.

Going Further
Consider the reaction for the commercial preparation of ammonia. Chemists use
the balanced equation below as their recipe for making ammonia.

N2 '1' 3H2 —) 2NH3

Since there is not a mole of nitrogen or hydrogen available for you to measure
the mass of on a balance, you’ll have to use the periodic table to figure these out.

1. What is the mass of 1 mole of N2?

2. What is the mass of 1 mole of H2?

3. What iS the mass of 1 mole of NH3?

4. If you had 2.0 moles of N2
a. How many moles of H2 would you need to react with all of the nitrogen?

b. How many moles of ammonia, NH3, could you produce (assuming enough
H2 is available)?

89

Appendix B-lll

5. What mass of ammonia could you make using 14.0 g of H2 and an excess of
N2?

6. What mass of H2 would you need to react with 42.0 g of N2?

90

Appendix B-IV

Lercentage Yield Lab

Background:

In class, you’ve Ieamed to calculate how much of a chemical product can be
made when measured amounts of chemical reactants are mixed. In this lab, you
will be using this information to predict how much product will be made; and then
calculating the percent yield from the amount that is actually recovered.

The reaction you will be working is probably a familiar one: baking soda will
react with vinegar to generate carbonic acid (which breaks up into water and
carbon dioxide gas) and sodium acetate.

 

 

 

 

 

 

 

 

 

 

 

Common Name Formula Chemical Name
Baking Soda NaHC03 Sodium Hydrogen Carbonate
Vlnegar HC2H3CO2 Acetic Acid

H2003 Carbonic Acid
Water H2O Dihydrogen Monoxide
Carbon Dioxide CO2 Carbon Dioxide
NaC2H3CO2 Sodium Acetate

 

Prelab Questions:

1. Write a balanced equation for the double replacement reaction between
sodium bromide, NaBr, and potassium chloride, KCI to produce sodium
chloride, NaCI, and potassium bromide, KBr.

2. If 25 grams of sodium bromide are mixed with a large amount of potassium
chloride, what will the theoretical yield of sodium chloride be?

3. If the actual yield from this reaction was 18 grams of sodium chloride, what
would the percent yield for this reaction be?

91

Appendix B-IV

4. Is the answer in question 3 reasonable? If so, explain why you think this was
a reasonable answer. If not, explain what is wrong with it and discuss
possible reasons one might get this answer in the laboratory.

5. What are some factors that might cause our percent yield to be greater than
100%? What are some factors that might cause it to be less than 100%?
Discuss specific cases of how both might happen.

6. In this lab, you will perform a reaction where sodium hydrogen carbonate will
react with an excess of acetic acid. By doing this, you will (hopefully) get
100% actual yield for the reaction.

For the reaction, you will need to use 0.05 moles of sodium hydrogen
carbonate. If more than 0.05 moles of sodium hydrogen carbonate is used.
the reaction will be too large and some of the products may pour over the Side
of the flask when we mix it with the acetic acid.

In the Space below, calculate how much sodium hydrogen carbonate you will

 

need for this lab:
For this lab, I will use grams of sodium hydrogen carbonate.
Procedure:

1. Measure out the weight of sodium hydrogen carbonate that you calculated the
pre- lab. Record the exact amount of sodium hydrogen carbonate that you
used in the Observations section.

92

Appendix B-IV

. Dissolve the sodium hydrogen carbonate in about 30 mL of water. Stir the
solution until most or all of it iS dissolved (if a little won’t dissolve, that’s OK).

. Weigh a 250 mL flask. Record its weight in the Observations section.

. Add the sodium hydrogen carbonate solution to the pre-weighed 250 mL
flask.

. Obtain 150 mL of acetic acid and slowly add it to the sodium hydrogen
carbonate solution. You will observe the formation of bubbles when the
acetic acid is added to the sodium hydrogen carbonate solution. Wait until
the bubbling subsides before adding more acetic acid. When all of the acetic
acid has been added, stir for two minutes before moving on to step 6.

. When the solution is again calm (there may be a few bubbles rising from the
bottom of the flask - this is normal), move the flask to a hot plate and heat it to
boiling. Be careful that the flask does not boil over because this will cause
you to lose some of the product of the reaction. Once the flask has started
boiling, gently set a watch glass on its mouth to keep any of the liquid inside
from splattering.

. When all of the liquid in the solution has boiled away, remove the flask from
the hot plate. The powder that you observe inside is the product of the
reaction, sodium acetate. Once the flask has had a few minutes to cool down
to room temperature, measure and record its weight.

. When this is done, you can rinse out the flask and any other glassware you
used. All waste can go down the Sink.

Observations:

Amount of sodium hydrogen carbonate used:

 

Weight of the empty 500 mL flask:

 

Weight of the flask, after the reaction:

 

93

Appendix B-IV
Analysis:

1. Write down the equation of the reaction you carried out in this lab. (Hint: The
reaction is discussed in the introduction to this lab.)

2. Using the exact weight of sodium hydrogen carbonate that you measured in
step 1 of the procedure and the equation that you wrote in the question
above, what is the theoretical yield of this reaction?

3. Calculate the actual yield of sodium acetate that you recovered in this lab,
using the weight of the empty flask and the weight of the flask alter the
reaction. Show your calculations below.

4. Using the actual yield of sodium acetate calculated in step 3 and the
theoretical yield of sodium acetate calculated in step 2, calculate the percent
yield of sodium acetate recovered in this lab. Show your calculations below.

5. Was your percent yield of sodium acetate 100%? What factors do you think
caused any error that you found? Explain, using specific examples.

Appendix B-IV

6. Do you think it is common for chemists to get 100% yields for chemical
reactions? Why or why not?

7. If you had to do this lab again, what would you do differently to improve your
answers? Explain, using Specific examples:

95

Appendix C

PowerPoint® Presentations

96

Appendix C-l

 

Symbols Used in Chemical Equations
Presentation

 

 

Symbols

 

Used in chemical equations

  

 

 

I “Yields”

- Indicates the result of a
reaction.

 

 

 

 

 

97

Appendix C-I

 

.3, .. ‘ . .,-,_<..,,_...j; 9.1.4: .
2-. 2...... _.._..__..__._._..__.__.__—_..

7

- Used in place of a Single arrow to

indicate a reversible reaction.

 

 

 

l

(S) -

- Follows the formula of a reactant or

product in the solid state.
- Used to indicate a precipitate.

- Why?

 

98

 

Appendix C-l

 

: - Used to indicate a precipitate.

CAUTION

. - For products only!

 

 

 

. . 4
a) 7

- Follows the formula of a reactant or
product in the liquid state.

 

99

 

Appendix C-I

 

- (aq)

- Follows the formula of a reactant or
product in an aqueous solution
(dissolved in water).

- NaCl (aq) is salt dissolved in water.
Saltwater!

. - I love SWlmmlng ln NaCI (aq) With a

, mask, snorkel & fins.
'3 § ’37 .

l J

 

 

(g) 4‘

- Follows the formula of a reactant or
product in the gaseous state.

- Steam is just water in the gaseous
state.

 

- To write steam into a formula
equation, write ”20(9)

37577 ‘3“(‘ J'- " “ “I: ‘ '
$42,..-“ 3...- .

L_

 

100

 

Appendix C-I

 

 

 

l

- Follows the formula of a reactant or
product in the gaseous state.

 

 

 

- Only use it for products!

 

 

 

A
—

 

 

- Indicates the reaction requires
heat in order to proceed.

 

 

101

 

Appendix C-l

 

2 atm ‘
——->

- Indicates the pressure required
for the reaction to proceed.

- 2 atmospheres in this case.

pressure
#

 

 

a]. 1 . .1 4‘ 7.. .
. _ -, - , .
W... .M“ _...,__._ ...¢.—..—._.——_———.

- Indicates the temperature
required for the reaction to
proceed.

- 0° C in this case.

temperature
—

 

 

102

 

Appendix C-I

 

MnO2
—>

 

- Indicates the formula of catalyst,
in this case manganese dioxide,
used to alter the rate of reaction.

catalyst
——->

 

 

 

 

 

Assignment

 

 

- Write a Symbol Story.

- Can you tell a story and replace words
with the symbols learned today?

- Read the grading Sheet.

 

 

 

 

 

 

103

Appendix C-ll

 

Activity Series
Presentation

 

Activity Series

A list of elements organized according
to the ease with which elements
undergo certain chemical reactions.

Page 266 Table 8-3

 

 

7Aclrvtly ti Mails

Ll

Rb React with cold HO and acids,
K replccmg nyaogen

Ba React with oxygcn lamng

Sr tildes

Cc

Na

! , M9 .dm.“m bu a dd
we -‘ = r”: '7 J 7 a : : -. t 3 -‘ '-. 71‘ ’7 7 7 I; 77! 7 77" ' ~ R. ( t n c
. 1 f it.“ t— -i i r. .C
In [Haida t..[l.,lli Ike..-‘ Luilb, watcrjcndaadc. Pl "‘9
" "I” hyaogen

nothing lower on the list can 2': mammals...
kick out an element that is on
higher on the list. 33 223.222.127.132...

Sn hyaogen
React truth oxygcn lormng
macs

 

React with oxygen, turning
tildes

Fairly unrecctrve, taming oxides

ally ndccctty

 

 

104

 

Appendix C-Il

 

&"1

[Examples ..

it Use the activity series to predict whether
the following reactions will occur.

Al + chl2 —>

Co + NaCl 9

 

 

L f'l’."q'I-i'\r""s j

[Examples

in Will rxn. Occur?
a What are products?
a Balance it!

MgCl2+Zn 9

AI+HZO9

 

105

 

Appendix C-II

 

 

[Examples

4 Will rxn. Occur?
4 What are products?
-. Balance it!

Cd+o2 9

l2 +KF e

.‘ 1,
at. may: n-..,.r.- .. .!

 

106

 

Appendix C-lll

 

Introduction to Stoichiometry
Presentation

 

Stoichiometry

 

 

E! The branch of chemistry that deals with the
mass relationships of elements in
compounds and the mass relationships
between reactions and products in a
chemical reaction.

 

 

Important stuff

 

 

El Moles

Cl Calculations with moles (the old factor
label)

[3 Balanced Equations

 

107

 

Appendix C-lll

 

Calculations with Moles

 

 

El What is the mass of 2 moleS of aluminum
oxide?

Cl Steps:
I Determine the formula of the compound.
I Find the molar mass of the compound.

I Multiply the molar mass by the number of
moles.

 

 

Calculations with Moles

 

 

C! What is the mass of 2 moles of aluminum
oxide, AIZO3?

El Molar Mass:
I For each element,

subscript x atomic mass

I Then add the element masses together to
9931'“? mass 0' WPQWPOFFId: __ ,

 

108

 

Appendix C-lll

 

Calculations with Moles

 

 

U PRACTICE!

El How many moles are there in 35.5 grams of
aluminum hydroxide?

 

 

Mole Ratio

E! A mole ratio is a conversion factor that relates the
amounts in moles of any two substances involved
in a chemical reaction.

 

 

E] To do anything with this, the equation must be
balanced.
Al203 —> Al+ O2

 

109

 

Appendix C-lll

 

Mole Ratio

 

 

2Al203 —> 4Al+ so2

III The coefficients represent the relative
amounts in moles of reactants and products.

D What is the ratio of Al to A|203?

4 mol Al
2 mol Al203

 

 

 

Mole Ratio

 

 

2AIZO3 -—> 4Al+ 302
El Possible mole ratios

2 mol Al203 or 4 mol Al
4 mol Al 2 mol AIZO3
E-mg'fi'ag O, _ 3 "‘0'92-
3 mol O2 2 mol A|203
4 mol Al or 3 mol O2
3 mo! 02 4 mol AI

 

 

 

 

 

 

110

 

Appendix C-lll

 

Where we’re going

 

 

C! We will calculate the amount of product we
expect to get from a reaction.

 

 

 

Mole Ratio
Amount 0! G'VEN mol unknown Amount of UNKNOWN
x :
substance (molS) mol given substance (molS)
Example

 

 

El How many moles of aluminum will be produced
from the decomposition of 13.0 moles of
AIZO3?

2A|2CD3 —> 4A! + 302

13.0 molAl203x 4mm“ = 26.0 mol Al

2 mol Al203

 

 

111

 

Appendix C-IV

 

Stoichiometry
Presentation

 

Stoichiometry

- A quantitative study of chemical changes.
' Like
- Calculation of how much product you will get in
a reaction.

Amount ofG'VEN mol unknown _ Amount of UNKNOWN

x
substance (010's) mol given substance (molS)

 

 

 

- Given the following unbalanced
equafion:

N20 + 02 —> N02

— Balance the equation.
- Find the mole ration of N02 to Oz.

 

112

 

Appendix C-IV

 

2NZO + so2 —> 4N02

- If 20 mol of NO2 form, how many moles of
O2 must have been consumed?

- Steps:
— Write down the given amount and compound.

— Multiply by a mole ratio that cancels the given
compound and yields the desired compound.

 

 

2N20 + 302 —-> 4N02

0 If 20 mol of NO2 form, how many moles of
O2 must have been consumed?

3molO
20moLNO 2 =
2x4rnolNCf2

=15molO2

 

 

 

 

 

 

113

 

Appendix C-IV

 

- Given the following balanced equation:

4NH3 +6NO —.> 5N2 +6H20

— Find the mole ration of NO to HZO.
— Find the mole ration of NO to NH3.

 

 

4NH3 +6NO —> 5N2 +6HZO

- If 0.240 mol of NH3 react according to the
above equation, how many moles of NO will
be consumed?

6molNO _
4motNFl3

= 0.360 mol NO

 

0.240 mama, x

 

 

 

 

 

114

 

Appendix C-IV

 

- Given the following balanced equation:

H2 +F2 —>, 2HF

-- How many grams of HF gas are produced
as 5 mol of fluorine react?

- Steps:
— Find moles HF produced.

— Multiply moles by molar mass of the compound
to get grams.

 

 

H2+F2 —-) 2HF

- How many grams of HF gas are produced as 5
mol of fluorine react?

2 mol HF
uneH'f

5% = 10 mol HF

 

 

x 20.019 _
10molHF 1molHF —200.19HF

 

 

 

 

 

115

 

Appendix C-V

 

Limiting Reactant and Percent Yield
Presentation

 

Limiting Reactant
Cu(s) + 2AgNO3m —> Cu(NO3 )2(aq) + 2Ag(s)

- The limiting reactant is the reactant that limits
the amount of product that can form in a
reaction.

— The reaction stops when the limiting reactant is
used up.

- The excess reactant is the reactant that is not
completely used up in a reaction.

 

 

Steps for solving a limiting reactant
problem

1. Write a balanced equation for the reaction.
2. Convert both reactant quantities to moles.

3. Determine the moles of the second reactant
required to react the first reactant.

4. The least amount in step #3 identifies the
limiting reactant. CIRCLE IT!

5. Use the number of moles of the limiting
reactant to determine amounts of product.

 

116

 

Appendix C-V

 

Practice Problem
Page 289

Some rocket engines use a mixture of hydrazine,
N2H4, and hydrogen peroxide, H202 as the
propellant. The reaction is given by the following
equafion:

NZH4 + 2H202 —> N2 + 4H20

a. Which is the limiting reactant in this reaction when
0.750 mol N2H4 is mixed with 0.500 mol of H202?

b. How much of the excess reactant, in moles, remains
unchanged?

c. How much of each product, in moles, iS formed?

 

 

NZH, N2 + 4H,o

0.750 0.500
mol mol

- Use moles of first reactant to determine
moles required of the second reactant.

2mol H202
1mol NZH4

= 1.5 mol H202

 

0.750 mol N2H4 x

- We only have 0.500 mol H202.
- The limiting reactant is H202.

 

117

 

Appendix C-V

 

N2H4 + 2H2O2 —> N2 + 4H20
0.750 0.500
mol mol

- How much N2H4 is left after all H202 is gone?

1mol N2H4
2mol H202

= 0.25 mol N2H4
- Only 0.25 mol N2H4 has reacted.

0.750mol NZH4 - 0.25 mol NZH4
0.5 mol NZH;

 

0.5 mol H202 x

 

 

N2H4 + 2H202 -> N2 +4H20
0.750 0.500
mol mol

- Use the limiting reactant to calculate amount

of products.

0.5 moleOzx 1m°'N2

2mol H202
~= 0.250 molN2;
4mol H20
2mol H202

= 1 .00moleo

 

0.5 mol H202 x

 

 

118

 

Appendix c-v

 

Percent Yield

- Theoretical Yield: The calculated amount
of product you expect to get in an
experiment

. Actual Yield: The amount of product you
actually get (measured amount).

- Percent Yield:

_ actual yield
theo. yield

 

% yield x100%

 

 

Practice Problem
Page 294

Methanol can be produced through the reaction of
CO and H2 in the presence of a catalyst. The
reaction is given by the following equation:

CO+2H2 Writ >CH30H

lf 75.0 g of CO reacts to produce 68.4 g of CH30H,
what is the percent yield of CH3OH?

 

 

119

 

Appendix C-V

 

co + 2H2—°‘“M—>CH3OH
75.09 68.49
- Calculate moles of CO.

75.09 cox 1mm CO
28019 CO

= 2.68 mol CO

- Use stoichiometry to calculate the mass
(theoretical yield) of CH3OH.

1mol CH3OH
1mol CO

= 2.68 mol CH3OH

 

2.68 mol CO x

 

 

 

co + 2H2 flny>CH3OH

 

 

 

75.09 68.49
- Calculate mass of CH30H.
x 32.05 9 CH3OH
2.68 molCH30H 1moICH30H
= 85.9 g CH30H
- Calculate % yield. .
% yield = actual yield x100%
theo. yleld
= 68.49 CHaOH x100%
85.99 CH30H
= 79.6%

 

120

 

Appendix D

Assessments

121

Appendix D-l

Introductory Survey

 

Circle the answer that best fits. Please answer honesfly.

1.

Do you plan on going to college
or trade school?

a. Yes

b. No

0. Maybe

d. ldon’t know

Will you take chemistry in
college?

Yes No

Will you study science or
medicine in college?

Yes No

What is a typical grade for you in
a math class?

A B C D

What is a typical grade for you in
a science class?

A B C D

Which class do you do best in?

a. Math b. Science
0. English d. Social Studies
a. All

Which class do you have trouble
with?

a. Math b. Science
0. English d. Social Studies
a. All

 

122

8. What do you find most distracting

in class?
a. Sounds b. Movement
0. Sights d. Lights

8. Other students

. Put an M by the two methods that

are most helpful to you when you
have trouble with a class. Put an
L by the two methods that are
least helpful to you.
Ask a hiend
Ask a question in class
_ Ask the teacher

Look at pictures or
diagrams in the text

__ Read the text

10.When you are thinking do you

Tap your pencil
Walk around
Doodle

Hum or Sing
Daydream
Other

”’9 $19 9'.“

11. When you attempt a story

problem in math you

a. Always solve them
b. Usually solve them
c. Solve them with help
d. Rarely solve them

Appendix D-l

 

12.Which part of science class do 15.Which part(s) of a lab do you
you like best? enjoy the most?
a. Labs b. Class work a. Writing my own procedure
0. Homework d. Lectures b. Measuring the chemicals
9. Videos 1'. Tests c. Mixing the chemicals
9. Other d. Doing the calculations
8. Making sense of the results
13. Which part of science class do f. Writing the lab report
you like least?
a. Labs b. Class work 16.Which part(s) of a lab do you
c. Homework d. Lectures enjoy the least?
a. Videos f. Tests a. Writing my own procedure
9. Other b. Measuring the chemicals
0. Mixing the chemicals
d. Doing the calculations
14. In which part of science class do 8. Making sense of the results
you learn the most? f. Writing the lab report
a. Labs b. Class work
d. Homework d. Lectures

123

Appendix D-Il

Chemical Reactions and Stoichiometry Pro-test

 

1. List 3 requirements for a correctly written chemical equation.
a.

 

b.

 

C.

 

2. Classify each of the following aS synthesis, decomposition, single
replacement, double replacement, or combustion.

a. 2H3P04 4H4P207 4" H20

 

b. HCI + AgN03 —>HN03 + AgCl

 

C. C7H15 4' 1102 -97C02 '1’ 8H20

 

d. AgN03 + Cu —cCuN03 + Ag

 

3. Balance each of the following reactions.

 

 

 

a. __NaCI+_F29_NaF+_CI2

b. H2 + O2 9 H2O

c. ‘.—— AlBr3 + _ K2SO4 9 __ KBr + _ Al2(SO4)3
d. _CH4+_O29_CO2+_H2O

124

Appendix D-ll

. What does the symbol (aq) mean in the following: AgN03 (aq) ?

. Use the activity series to predict whether a given reaction will occur and what
the products will be. If a reaction will occur, write and balance the reaction. If
no reaction will occur, just write “no reaction.”

a. Mg (3) + steam 9

b. Ch (9) + MgBr2 (aq) 9

d. Ni (3) 4' H20 (I) 9

. Define stoichiometry and explain what chemists use stoichiometry for.

125

Appendix D-Il

7. Describe a method for determining which of two reactants is the limiting
reactant.

8. Compare actual yield to theoretical yield.

Write the answers to the following questions on the line to the left, and
show your work in the space provided.

9. For the reaction Pb(N03)2 + 2Kl9 Pbl2 + 2 KNOa,
how many moles of lead iodide are produced from
300 g of potassium iodide?

10. For the reaction 2KCIO3 9 2 KCI +3 02, how many
grams of potassium chlorate are required to produce
160 g of oxygen?

126

Appendix D-Ill

Chemical Symbol Story Grading Sheet

Student name:

 

Period: 1 2 3 4 5 6 Date:

 

Apgarance (4 mints total):

This grade sheet accompanies your story (1): _
The writing is neat and presentable (2): _

Teacher

Evaluation

The title is appropriate, meaningful, and interesting (1): _

Scientific Content (12 mints total):

Concepts used are appropriate and accurate (5): _
Vocabulary is appropriate and used correctly (4): _

\fisuals such as symbols, drawings, diagrams or pictures are
used in an appropriate way to add information and interest (3):

Stog (10 points total):
0

There is a clear theme to the story (2): _

The plot centers around, develops, and resolves a problem. (2):

0 We story has an engaging, interesting conflict that captures and

holds the attention of the reader. (2): _

Each event or episode is important to the meaning of the plot.

(1): _
The plot follows logically. (2): _
The story has a consistent point of view. (1 ): _

Mechanics (4 points total):

Grammar is correctly used within the format (2): _
There are zero Spelling errors (2): _

 

 

Total Points:

 

 

127

Section 1 Exit Survey

Appendix D-IV

 

Describe how successfully ycu
can use these skills

Some-

Rarely times Often Usually Always

 

Identify observations that a
chemical reaction has taken place.

 

Identify a correctly written
chemical equation.

 

Write a word equation from a
_given formula equation.

 

Write a formula equation from a
_given word equation.

 

Balance a formula equation.

 

Classify a chemical equation
according to it’s type.

 

Predict the products of Simple
reactions givfen the reactants.

 

Use the activity series to predict
whether a reaction will occur and
what the products will be.

 

 

 

 

 

 

 

 

Describe how helpth these

actlvmes were

Not Somewhat Helpfui Very

 

PowerPoint® Presentations

Helpful Helpful Helpful

 

Burger Chem Lessons

 

S’mores Lab

 

Balancing Race

 

Symbol Stories

 

Types of Reactions Lab

 

Recycling Copper Lab

 

Reading the text

 

Homework Papers

 

 

 

 

 

 

 

128

Appendix D-V

Section 2 Exit Survey

 

Describe how successfully you

Rarely SF’me' Often Usually Always

 

can use these skills:
Write a mole ratio relating two
substances in a chemical equation.

times

 

Calculate the amount in moles of a

reactant or product from the amount

in moles of a different reactant or
roduct.

 

Calculate the mass of a reactant or
product from the amount in moles of
a different reactant or product.

 

Calculate the amount in moles of a
reactant or product from the mass
of a different reactant or product.

 

Calculate the maSS of a reactant or
product from the mass of a different
reactant or product.

 

Identify the limiting reactant in a
chemical reaction.

 

Calculate the amount of product
(either mass or moles) in a limiting
reactant problem.

 

Calculate percent yield, given the
actual yield and quantity of a
reactant.

 

 

 

 

 

 

 

 

Describe how helpful these

activities were:

Not Somewhat Helpful Very

 

PowerPoint® Presentations

Helpful Helpful Helpful

 

Burger Chem Lessons

 

Finding Coefficients Lab

 

Percent Yield Lab

 

Reading the text

 

 

 

Homework Papers

 

 

 

 

 

129

Appendix D-VI

Chemical Reactions and Stoichiometry Post-test

 

1.

List 3 requirements for a correctly written chemical equation.
a.

 

b.

 

C.

 

Classify each of the following as synthesis, decomposition, Single
replacement, double replacement, or combustion.

a. 2H3P04 —§H4P207 + H20

 

b. HCI + AgNOa -+HN03 + AgCl

 

C. C7H13 + 1102 —§7C02 + 8H20

 

d. AgN03 + Cu —+CuN03 + Ag

 

Balance each of the following reactions.

 

 

 

a. __NaCl+_F29__NaF+_Cl2

b. H2 + 02 9 H2O

c. _ AlBr3 + __ K2SO4 9 _ KBr + __ AI2(SO4)3
d. _CH4+__O2 9_CO2+__H2O

130

Appendix D-Vl

. What does the symbol (aq) mean in the following: AgNO;; (2..) ?

. Use the activity series to predict whether a given reaction will occur and what
the products will be. If a reaction will occur, write and balance the reaction. If
no reaction will occur, just write “no reaction.”

a. Mg (3) + steam 9

b. Ci2 (g) + MQBT2 (aq) 9

C. Ni (5) + CUCI (aq) 9

d. Ni (3) '1' H20 (l) 9

. Define stoichiometry and explain what chemists use stoichiometry for.

131

Appendix D-VI

7. Describe a method for determining which of two reactants is the limiting
reactant.

8. Compare actual yield to theoretical yield.

Write the answers to the following questions on the line to the left. and
show your work in the space provided.

9. For the reaction Pb(NOa)2 + 2Kl9 Pbl2 + 2 KNO3,
how many moles of lead iodide are produced from
300 g of potassium iodide?

10. For the reaction 2KCl03 9 2 KCI +3 O2, how many
grams of potassium chlorate are required to produce
160 g of oxygen?

132

Appendix D-Vll
Test Self Evaluation

Test Name: Test Date:

 

Score: out of 9 Percentage:

1. What was the general topic covered by the test?

2. How did I prepare for the test?

3. What have I Ieamed?

4. What do I need to improve?

5. How might I have prepared more effectively?

6. Am I satisfied with this performance?

133

%

 

Appendix D-Vlll
Weekly Reflections

Week Ending Date:

 

1. Concept: State the concept being Ieamed.

2. Process: Describe the process you (the class) used to Ieam the concept

3. Attitude: Describe your attitude toward the concept, the process, etc. Tell how
you feel about what you are Ieaming.

 

Appendix D-Vlll
ConsenLLettLr

Dear Parent/Guardians and Students:

 

For the past three years, I have been enrolled as a graduate student in Michigan State
University’s Division of Science and Mathematics Education (DSM E). I have chosen to
do my thesis work on the implementation of a unit on stoichiometry in my chemistry
classes. Stoichiometry is the quantitative relationship between reactants and products in
a chemical reaction. My goal in teaching this unit is to give students a solid
understanding of the relationship between amounts in chemical reactions through
providing both traditional and multimedia instruction combined with memorable hands-on
activities and laboratory experiences. An important aspect of this work is obtaining data
about the effectiveness of this unit, which in turn will be the foundation of my thesis.

In order to evaluate the learning process, data will be collected from pre and post tests,
responses from activities and laboratory experiments and surveys that will be given
throughout the unit. Wlth your permission I would like to include your child’s data in my
thesis. Your child’s privacy will be protected to the extent that is allowable by law, and at
no time will the student’s name be used or connected with any part of my thesis paper.
All data will remain confidential.

Participation in this study is voluntary. Your child will receive no penalty in regard to their
grade should you deny permission for use of their data. Participation in this study will
neither increase nor decrease the amount of work that is required by your child. All
assignments will be graded within the regular framework of the course as set forth in the
syllabus.

Please complete the attached form and return it to me by DATE. Should you have any
questions or concerns feel free to contact me at Redford Union High School (313) 242-
6732 or by email at pakkalj@redfordu.k12.mi.us. Questions about the thesis project may
also be directed to Dr. Merle Heidemann at DSME 118 N. Kedzie, Michigan State
University, East Lansing, MI, 48824, by phone at (517) 432-2152 ext. 107 or by email at
heidem82@msu.edu.

If you have any questions or concerns regarding your rights as a study participant, you
may contact Peter Vasilenko, Ph.D., Chair of the University Committee on Research
Involving Human Subjects (UCRIHS) by phone: (517) 355-2180, fax: (517) 432-4503,
email: ucrihs@msu.edu, or regular mail: 202 Olds Hall, East Lansing, MI 48824.

Sincerely,
UCRIHS APPROVAL FOR
THIS project EXPIRES:
Jennifer Pakkala
Chemistry Teacher SEP 1 5 2005
Redford Union High School
(313) 24243732 moflgfroewmfll Wrgmlt
ABOVE DATE TO CONTINUE

Please fill out the consent Information on the attached page.

135

Appendix o-vm

I voluntarily agree to have participate in this study.
(Print Student Name)

Please check all that apply.

Data:

I give Mrs. Pakkala permission to use data generated from my child’s work in this
class. All data from my child shall remain confidential.

I do not wish to have my child’s work used in this thesis project. I acknowledge
that my child’s work will be graded in the same manner regardless of their
participation.

lmgge:
I give Mrs. Pakkala permission to use images of my child through photography
during her work on this thesis project. My child will not be identified in these
images.

I do not wish to have my child’s image used at any time during this thesis project.

 

 

(Parenthuardian Signature) (Date)

I voluntarily agree to participate in this thesis project.

 

 

(Student Signature) (Date)

136

BIBLIOGRAPHY

137

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