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This is to certify that the
thesis entitled

IMPROVING STUDENT COMPREHENSION OF
STOICHIOMETRIC CONCEPTS

presented by

Connie Lynn Bannick Kemner

has been accepted towards fulfillment
of the requirements for the

Masters degree in Interdepartmental Physical
Science

 

 

7L<11W

Major Professor's Signature

17 Ada 07'
Date

MSU is an afiinnative-action, equal-opportunity employer

 

 

PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before date due.
MAY BE RECALLED with earlier due date if requested.

 

DATE DUE

DATE DUE

DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6/07 p:/ClRC/DateDue.indd-p.1

 

IMPROVING STUDENT COMPREHENSION OF
STOICHIOMETRIC CONCEPTS
By

Connie Lynn Bannick Kemner

A THESIS

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

MASTER OF SCIENCE

Interdepartmental Physical Science

2007

Merle Heidemann

ABSTRACT

IMPROVING STUDENT COMPREHENSION OF STOICHIOMETRIC
CONCEPTS

By
Connie Lynn Bannick Kemner
Stoichiometry is a mathematical Chemistry concept. One use of stoichiometry is to

determine how much product can be formed from a given amount of reactants.

The purpose of this study was to teach a variety of stoichiometric concepts to high school
students. During the unit, students learned to do conversions related to balanced
chemical equations, determine which reactant was the limiting reactant, and to determine
percent yield. This was accomplished using lecture, class discussion, working through
sample problems as a class, and a variety of laboratory activities. The majority of the
unit was spent doing activities with the goal that students would be more engaged than if
they were simply doing homework problems. Data were collected using pre-unit and

post-unit surveys, pre-unit and post-unit tests, and answers fiom student work.

Test averages from the current year and 2005-2006 year were compared. Although the
averages were not significantly different, the grades were higher this year. Also, based
on student cements and teacher observations, the students seemed to enjoy the unit

more and retained the information longer compared to previous years.

ACKNOWLEDGEMENTS

Special thanks go to my husband, Mark, for helping whenever I needed it and having the
patience to do so.

Thank you also to my parents who have always taught me that I can do whatever I put my
mind to doing.

One last thank you goes to Dr. and Mrs. Boyd Ellis who were generous enough to allow
me to live in their home while I did much of my degree work.

iii

TABLE OF CONTENTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

List of Tables v
List of Figures vi
Introduction 1
Implementation of the Unit 8
Results/Evaluation 19
Discussion and Conclusion 35
Bibliography 40
Appendices - - - 42
Appendix A — Unit Outlines 43

Al Proposed Unit Outline 44

A2 Unit Outline as Presented 45

Appendix B — Consent Form 46
Appendix C - Surveys 50

Cl Pre-Unit Survey 51

C2 Post-Unit Survey 58

Appendix D — Activities 55

D1 Stoichiometry Scavenger Hunt -56

D2 Stoichiometry Manipulatives 58

D3 Teacher Demonstrations 59

D4 Al + CuClz Lab 61

D5 Percent NaHCO; in a Tablet Lab 64

D6 Determination of Percent Yield Lab -- 66

D7 Kitchen Stoichiometry/Fizzy Drinks Activity 68

D8 S’more Stoichiometry Activity 70

D9 Decomposition of Baking Soda Lab 72

mo Determining Mass of CO; Lab - - 74

D11 Balloon Lab 76

D12 Making Chalk Lab 78

D13 Air Bag Activity 81

Appendix E — Assessment 83

El Pre-test - 84

E2 Post-Lab Quiw 86

E3 Stoichiometry Quiz #2 87

E4 Stoichiometry Quiz #3 88

E5 Post-test 89

Appendix F - Student Data 94

F1 Student Scores 95

F2 Student Response Scores for Pretest Questions 99

F3 Student Response Scores for Posttest Questions? - 101

 

iv

LIST OF TABLES

 

 

 

 

 

 

Table l — Unit outline 9
Table 2 - Activity Scores- - - - - - - 30
Table 3 - Student Scores for Activities (hours 1, 2, & 4) 95
Table 4 - Student Scores for Activities (hours 5 & 6)- _ - - -- 96
Table 5 - Student Scores for Quizzes and Posttest (hours 1, 2, & 4) 97
Table 6 — Student Scores for Quizzes and Posttest (hours 5 & 6) -- - - 98
Table 7 — Student response scores for pretest questions (hours 1, 2, & 4).. ............. 99
Table 8 - Student response scores for pretest questions (hours 5 & 6) - 100

 

Table 9 — Student response scores for posttest questions (hours 1, 2, & 4)..............101

Table 10 — Student response scores for posttest questions (hours 5 & 6) ................. 102

LIST OF FIGURES

Figure 1 — Student responses for common pre- and posttest questions 19

 

Figure 2 - How students perceived their ability to perform specific conversions from
the previous unit 21

 

Figure 3 — How students perceived their ability to perform specific conversions from
the previous unit at the end of the stoichiometry unit - - _- - -- A - 22

 

Figure 4 - How students perceived their ability to perform calculations presented
during the stoichiometry unit 2‘3

 

 

Figure 5 — Students favorite and least favorite classes- - - - _ 24

Figure 6 - Student ranking of the most and least helpful parts of science classes....24

 

Figure 7 — What students do when they study A A A AA A A 25
Figure 8 - What strategies students use when working on story problems ............. 26
Figure 9 — What strategies students use when they have problems in a class ............ 26

Figure 10 — How students felt about the activities they completed during the unit...27

 

 

 

 

 

Figure 11 — Student rankings of the activities from the unitAA AA -A - AA 28
Figure 12 - Student scores for Al + CuClz Lab Quiz 31
Figure 13 — Student scores for Stoichiometry Quiz #2 -_ -- 32
Figure 14 — Student scores for Stoichiometry Quiz #3 33
Figure 15 — Student scores for Stoichiometry Unit Test- - _ A A A 34
Figure 16 — Manipulative, first version 58

 

 

Figure 17 — Manipulative, second version A _ AAAAAAAAAAAA A A 58

vi

INTRODUCTION

I chose to improve the stoichiometry unit where students are asked to mathematically

interpret chemical equations. By the end of the unit, students should be able to:

Define the term stoichiometry.

Use moles of one substance to determine moles of another substance.

Use the grams of one substance to find the grams of another substance.

Use the grams of one substance to find the liters of another substance.

Use the liters of one substance to find the grams of another substance.

Use the liters of one substance to find the liters of another substance.

Use the grams of two reactants to determine the amount of product that can be

made.

Use lab data along with the expected amount of product to determine the percent

yield.

This unit is generally taught during the middle of the second semester (mid-March

through mid-April). At this point, students have learned about the atom, the periodic

table, how to do basic conversions using dimensional analysis, how to balance chemical

equations, and the mole concept. Following this unit is one on how kinetic-molecular

theory applies to the different states of matter and a unit on solutions, acids, and bases.

At the end of the year, students complete a written final exam and a project exam that

incorporates all of the key ideas from the second semester.

I chose to work on this topic because it has been a source of fi'ustration for many of my
students over the past several years. The complaints are generally based on the
mathematics involved that students often believe do not make sense. I model how to
solve the problems and involve the students in practicing the skills needed to solve the
problems, but that is not always enough. I feel that I am doing too much talking during
the unit which bores the students and me. In addition, I would like the students to be
more actively engaged in activities as that should lead to better understanding. If things
go well, some of them may even decide that stoichiometry and related problems can be

fun.

Stoichiometry is often a difficult topic for students taking an introductory Chemistry
course. Thismaybebecausethetopicistooabstractoritmaybebecausethelanguage
used is done so in a way that is unfamiliar (Huddle, 1996). I believe that both of these
are contributing factors for my students. One way to eliminate the language barrier is to
break down large words into their components. To ease the issue of abstractness, it helps
to work on making the process of stoichiometry as simple as possible (Poole, 1989).
Another way to help students with this abstract topic is to teach them to translate the
symbolic information given in a chemical equation into something more tangible (Koch,
1995). In my classroom, I try to model the process of doing stoichiometric conversions
and then guide students through some sample problems to familiarize them with the
concepts before asking them to attempt problems on their own. I also try to incorporate
lab activities so they have a hands-on experience. They can measure masses of reactants

and products then compare them to the results of their conversions.

Beyond the issue of difficulty, the students are not always given enough opportunities to
make their own connections to stoichiometric concepts. Lecture material and a few
worksheets supplemented by a lab activity or two were not sufficient. This lecture driven
method works for some learners but not all of them (Lawrence, 1984). This is because
not all students learn the same way. Some are more auditory so the spoken word works
well for them. Others have a need to move and interact with the subject matter or with
other students (Dunn and Griggs, 2000). In my classroom, I try to vary activities from
day to day so that students are not sitting through lecture several days a week. Even

during lectures, I try to spend time modeling and coaching students in their learning.

Since it is not always practical to design individual lessons every day for each student, it
is important to use activities that involve different methods of learning like labs where
there is hands-on learning being coupled with what they can observe visually.
Developing such lessons allows students to develop other learning styles instead of
relying on just one (Bold, 2004). By addressing different learning styles, lessons can be
more meaningful for all students (Boyles, 1997). It also more closely simulates the real
world as learning outside of the classroom is not all auditory, all visual, or all kinesthetic
(Jensen, 2005). Including more hands-on activities that involve more than just the art of
observation allows students to become involved and give them a sense of actually doing
science instead of being a mere bystander to the process (Zemelman, 2005). Allowing
students to interact with the material through their sense of touch, taste, and/or smell in

addition to what they can observe visually can also assist students in their learning

experiences (Reiff, 1992). This is where lab activities can be useful. Students now have
chemicals reacting and changing right before their eyes. Whenever it is safe, I give
students permission to touch or smell the chemicals so that they have more sensory input
from the activity. By giving students this first-hand experience with the subject matter
instead of relying on rote learning, their learning process may be improved (Huddle,
1996). In addition to lab activities, another form of hands-on learning is through the use
of manipulatives (Dunn and Griggs, 2000). Internet-based assignments may also be
usefiil, especially if there is access to programs and activities to help them to visualize
more abstract topics (Arasasingham, 2005). Throughout the year, I schedule time for
students to work with computers. On computer days, students are given a task and some
suggested websites to visit. This seems to make learning more fun as the students are
much more involved with computer projects than they are when they are asked to read
the text to find the same information. These projects culminate with the students
presenting their findings to the class through media presentations. This allows the
students to go from the role of being a learner to being a teacher and I step aside during
their teaching. My interaction at that point is to ask clarifying questions and make sure

that they address any questions their classmates might have.

If a student can see a connection between an activity and their everyday life, they are
more likely to consider it a relevant task (Sumrall, 1991). This experiential learning
allows the student to connect ideas from this unit to prior learning as well as to new
topics (Stemberg, 2000). When students are allowed to make sense of the topic they are

more likely to remember the information, not just for the upcoming test, but for some

time into the future (Hermn, 1996). Throughout the year, I try to give students chances
to connect with the material through labs that mimic real-world situations. One such
activity is the dehydration of gypsum and plaster of Paris. Groups are asked to act as a
chemical analysis company and determine the composition of each material. In the
process, they must create invoices, develop procedures, and create reports to discuss their
findings. This lab takes a few days to complete, but students are generally involved and
active throughout the process. Through the use of a lab that utilizes using everyday

materials, students should be able connect aspects of their learning to their own lives.

The learning process can also be improved by allowing students to work in groups of two
to five students each. This gives an outlet to those students who have trouble interacting
with adults. They may now interact with their classmates in a more relaxed atmosphere.
This allows the students to divide up the task and work more effectively (Dunn and
Dunn, 2000). It also allows them to do some thinking aloud and get feedback from their
classmates or from the instructor (Jeon, 2005). After attending several brain-based
learning workshops at our school a few years ago, I reorganized my classroom so tint
students are seated in small groups instead of the traditional rows. Students are now
being encouraged to interact with each other and are able to do so without the disruptions
I used to have when they were in rows because they are in closer proximity to the person

they need to address.

For the thesis project, I set out to develop a stoichiometry unit that would address

different methods of learning, include a variety of hands-on activities, allow students to

be experiential learners, and place students into small learning groups. To accomplish
this, I planned some teacher-led activities such as lecture and note-taking along with
some student-centered activities. These activities would alternate throughout the unit.
Each segment of the unit would start with a lecture and note-taking activity to give
students background information and an introduction to the skills they would develop in
that segment. The segment would then bring in student-centered, hands-on activities.
This would be the basis for turning the stoichiometry unit into a more interactive unit for
the students (Hassard 2005). If all went well with the unit, this year’s students would
have a better understanding of stoichiometry than those in previous years and that
understanding would stay with them. This could be measured by comparing data from
this year’s students to data from previous years for the unit test as well as final exam and

project data.

Lake Shore High School is a public school for students in ninth through twelfth grades in
Saint Clair Shores, Michigan. The school had an enrollment of 1,098 students for the
second count of the 2006-2007 school year. Our school is a school of choice and there
were 145 students in the building taking advantage of that opportunity. A majority
(89.43%) of the students who attend Lake Shore are identified as White. The remaining
students are identified as Black (4.55%), Asian (1.09%), Hispanic/Latino (1.09%),
American Indian (3.20%), and Multi-Racial or No response (0.64%). More than a
quarter (28.23%) of our students received free or reduced price lunches. The unit was
presented to five sections of Chemistry with a total of 136 students. That represents one

senior, 28 juniors, and 107 sophomores. The students taking Chemistry generally

reflected the previously listed ethnic breakdown. The data in this study were generated
by 34 students who submitted signed consent forms as well as from anonymous pre- and
post-surveys (Appendices B & C). This number is low compared to the number of
students in taking Chemistry classes. Possible reasons for low participation were that the
consent forms were not given until the end of the unit, at the request of the review board,
which ended just before Spring Break so there were many students focused on the break
rather than schoolwork and students in our school are not likely to return any materials if
they are not going to receive credit for doing so. Despite the low number of students
participating in the study, the group reflected the wide range of abilities present in the

entire five sections of Chemistry students.

IMPLEMENTATION OF THE UNIT

Prior to the 2007-2008 school year, there were a number of labs being done during the
stoichiometry unit, but I felt that some of them were not working well in terms of student
understanding and some were almost too long to complete during a single class period.
This was one reason I chose to improve this unit. The other reason was because this unit
was the one that presented the most difficulty for students in previous units. The main
goal of my research was to find shorter, and perhaps less involved, labs that would
engage students and increase their abilities to comprehend stoichiometric concepts. I also
wanted to develop a device that could assist my students in the process of learning
stoichiometry. This device would have conversion factors on it that my students could
manipulate while they were practicing the various types of stoichiometric calculations.
When I arrived on campus for the summer research, I started looking for activities that
would support the learning of stoichiometry by actively engaging students in classroom
activities. My research (intemet, alternate textbooks, and modification of current
activities) resulted in the development or adaptation of eleven activities (Appendix A).
Near the end of the research course, I went back to my initial idea of developing a
manipulative to assist students with the various conversion factors involved in
stoichiometric problems. I found some mailing tubes, dowel rods, and fim foam in the
store room and began forming the first manipulative. After some sawing, gluing, and
boring holes with a hot object, I had one working manipulative (Appendix D, Figure 16).
That one rmnipulative took a lot longer to put together than I thought it might, so I sat

down to think about how I could simplify it. I then created a modified version that took

much less time to build (Appendix D, Figure 17). This modified version would later be

replicated so that I had a set to use in class.

This year, the stoichiometry unit was taught following a unit on balancing equations and
one on the mole concept that also introduced dimensional analysis. This represents a
change over previous years where the balancing equations unit was in the middle of the
mole concept and stoichiometry units. The change was done because I thought this order
might be more beneficial to the students. The intended benefit for the students was that
the dimensional analysis would still be fresh in their minds as they began to learn about
stoichiometry and the units would transition better. There were initially eleven activities
planned for this unit (Appendix A). In the end, seven of these activities were used and
the final stoichiometry unit outline which includes objectives for each activity is included

in Table 1.

Table 1 - Unit outline with objectives

 

 

 

To ics Activities Objectives

0 What is 0 Lecture 0 Define the term stoichiometry.
Stoichiometry? 0 Class Discussion 0 Use moles of one substance to

o Mole-Mole & Practice determine moles of another substance.
Problems Problems

0 Basic Types of 0 Lecture 0 Use the grams of one substance to find
Stoichiometry 0 Class Discussion the grams of another substance.
Problems & Practice 0 Use the grams of one substance to find

Problems the liters of another substance.

0 Use the liters of one substance to find
the grams of another substance.

0 Use the liters of one substance to find
the liters of another substance.

 

 

o How to Use 0 Stoichiometry 0 Define the term stoichiometry.
Stoichiometry Scavenger Hunt 0 Use moles of one substance to
(intemet-based) determine moles of another substance.

 

 

0 Use the grams of one substance to find

 

 

 

the grams of another substance.

 

 

 

 

 

 

 

 

 

 

Stoichiometric Al + CuClz Lab Use moles of one substance to

Conversions in determine moles of another substance.

the Laboratory Use the grams of one substance to find
the grams of another substance.

Limiting Post-lab Quiz — Use the grams of two reactants to

Reactants Cu + AgNO3 Lab determine the amount of product that

Percent Yield Limiting can be made.

Reactants & Use lab data along with the expected
Percent Yield amount of product to determine the
percent yield.

Stoichiometric Percent NaHC03 Use the grams of one substance to find

Conversions in in a Tablet Lab the grams of another substance.

the Laboratory Use lab data along with the expected

Using Lab Data amount of product to determine the

to Calculate percent yield.

Percent Yield

Using Lab Data Stoichiometry Use the grams of one substance to find

to Calculate Quiz #2 the grams of another substance.

Percent Yield Determination of Use lab data along with the expected

Percent Yield Lab amount of product to determine the
percentlield.

Using Lab Data Decomposition of Use the grams of one substance to find

to Determine Baking Soda Lab the grams of another substance.

Which Reaction

Occm'red

Using Lab Data Determining Use the grams of one substance to find

to Calculate Mass of C02 Lab the grams of another substance.

Percent Yield Use lab data along with the expected
amount of product to determine the
percent yield.

Using Stoichiometry Use the grams of one substance to find

Stoichiometry Quiz #3 the grams of another substance.

to Make the Air Bag Activity

Ideal Air Bag (part 1)

Using Air Bag Activity Use the grams of one substance to find

Stoichiometry (part II) the grams of another substance.

to Make the

Ideal Air Bag

Review Define the term stoichiometry.

 

 

Use moles of one substance to
determine moles of another substance.
Use the grams of one substance to find
the grams of another substance.

Use the grams of one substance to find

 

10

 

 

the liters of another substance.

0 Use the liters of one substance to find
the grams of another substance.

0 Use the liters of one substance to find
the liters of another substance.

0 Use the grams of two reactants to
determine the amount of product that
can be made.

0 Use lab data along with the expected
amount of product to determine the
percengield.

 

o Stoichiometry test 0 Define the term stoichiometry.

Use moles of one substance to
determine moles of another substance.

0 Use the grams of one substance to find
the grams of another substance.

0 Use the grams of one substance to find
the liters of another substance.

0 Use the liters of one substance to find
the grams of another substance.

0 Use the liters of one substance to find
the liters of another substance.

0 Use the grams of two reactants to
determine the amount of product that
can be made.

0 Use lab data along with the expected
amount of product to determine the
percent yield.

 

 

 

 

o Post-Unit Survey

 

The unit started with each student being asked to complete an anonymous Pre—Unit
survey (Appendix C) and a Pretest (Appendix E). This was to assist in determining
student abilities fi'om previous units and their attitudes about science as well as school in
general. The first two days were spent going over basic stoichiometry information.
These two class days were similar to previous years where most students took notes and
practiced using the math. From there, I began introducing activities that were developed
during the research summer. There was one more day of lecture in the middle of the

activities. During this lecture, we covered how to determine the limiting reactant and

II

 

how to calculate percent yield. This included taking notes and working through some
sample problems. While discussing limiting reactants, we talked about how not using the
stoichiometric ratio of chemicals during a lab activity would result in wasted materials as
one reactant would be in excess. After students took their Posttests (Appendix E), they

finished the unit by completing a Post-unit Survey (Appendix C).

Following is a description of the activities and assessments used during the unit. A
qualitative analysis accompanies each activity description.

Activities
1. Stoichiometry Scavenger Hunt (Appendix D)

This activity required students to work in pairs while doing some internet research
related to the stoichiometry concept and how to solve stoichio metric problems.
Students visited selected internet sites, recorded information, and completed related
problems. To assist students with the problem completion, students were allowed to
use the stoichiometry manipulatives (Appendix D). The students were very engaged
during the Stoichiometry Scavenger Hunt and worked well during the class period.
Those who chose to use the stoichiometry manipulatives reported positive
experiences and several would go on to use them for other assignments during the
unit. When asked how they liked the activity, I received several comments of “It’s
easy.” Generally, students had little trouble with the research aspect of the
assignment. The difficulties were mostly related to the mathematical problem solving

which was still very new to them.

2. Aluminum + Copper (II) Chloride Lab (Appendix D)

12

This lab required students to place a coil of aluminum wire into a solution of copper
(II) chloride and filter out the solid copper that was produced from the single
replacement reaction. If groups carefiilly followed the procedure, they would have a
mass of copper product that would closely resemble, if not match, the stoichiometric
calculations that were based on the amount of aluminum and copper (II) chloride
consumed in the reaction. The biggest problem encountered during this part of the
lab was that students either did not read the lab in advance or were not carefully
reading during the activity. The filtered product was to be dried overnight and
massed during the next class period. This lab was adequately effective, but it was not
as good as I expected. This was likely because there were several students who had
not read through the lab prior to class and those groups had difficulty finishing on
time. The lab results for this lab did not turn out as well as I hoped. One big problem
was that students were having trouble completing the calculations and this was likely
due to the newness of the stoichiometry concept. Another problem came from
students not being able to clearly see a color change in the aqueous solution.

. Percent NaHC03 in a Tablet Lab (Appendix E)

For this lab, students were given an effervescent tablet containing sodium hydrogen
carbonate and determined the individual masses of the tablet and a beaker of water.
After the reaction was completed, they found the mass again so they could determine
the amount of carbon dioxide produced and use their knowledge of stoichiometric
conversions to determine the amount of sodium hydrogen carbonate originally in the
tablet. They then compared their answer to the amount listed on the package and

found their percent yield. This lab took very little time to complete, so there was time

13

4.

5.

for students to work on their calculations during class and get help when needed.
There were no major difficulties with this lab and students were generally able to
complete the activity to a satisfactory level. By this time, students were gaining a
little confidence in their abilities and were not as fi'ustrated as they were with the
previous lab.

Determination of Percent Yield Lab (Appendix D)

Students measured an amount of sodium hydrogen carbonate and used stoichimetric
conversion to determine how much sodium chloride could be produced by reacting
hydrochloric acid with sodium hydrogen carbonate. They then heated the resulting
mixture to drive off the water and leave behind sodium chloride crystals. Groups
who carefully followed the procedure would have typical sodium chloride crystals at
the end of the lab. Not all groups were able to produce typical crystals. Some had
powdered product that was white, yellow, or light brown which I suspect may have
been related to students using a heat setting that was too high, using too much
hydrochloric acid, or possibly having some sort of other contamination in their
beakers. For this reason, I would like to try the lab again and change the heating
portion to allow the liquid to evaporate over a couple of days before using the hot
plate. After the product formed, students measured the mass and determined percent
yield by comparing their product mass to the mass they calculated using
stoichiometry. This was another activity that most students were able to complete
satisfactorily.

Decomposition of Baking Soda Lab (Appendix D)

14

6.

Students measured the mass of a small amount of baking soda (sodium hydrogen
carbonate) in a crucible. The crucible was then heated for three to five minutes to
assist in the decomposition process. When the crucible was cool, the mass was taken
again. The crucible was heated for another brief period, cooled, and measured. This
process was repeated until the mass changed by no more than one one-hundredth of a
gram which signaled that the decomposition process was completed. While
completing the heating and cooling cycles, students were asked to translate three
word equations into balanced formula equations. Based on the starting amount of
baking soda and the balanced equations, they were asked to calculate how much solid
product could be formed. When they finished the heating and cooling cycles, they
were asked to compare their measured data to the calculations so they could
determine which of the three reactions took place when the baking soda was heated.
Students had little trouble with the technique involved in the Decomposition of
Baking Soda Lab and this was due mainly to them spending almost a week using the
same skills to dehydrate gypsum and plaster of Paris. That gave them more
confidence in their abilities and a willingness to attempt the lab. The biggest problem
students had was in determining which reaction occurred. It appears that they are too
accustomed to doing cookbook-style labs where they simply get data that they do not
have to analyze. Most students completed this activity satisfactorily.

Determining Mass of C02 Lab (Appendix D)

Students were asked to determine the mass of a small amount of sodium hydrogen
carbonate as well as the mass of 100 milliliters of vinegar (a solution of acetic acid

and water). They then had to pour the vinegar into the sodium hydrogen carbonate

15

slowly so that the fizzing did not result in a loss of any liquid product. They were
asked to use stoichiometry to determine the expected amount of carbon dioxide based
on their starting amount of sodium hydrogen carbonate. Students used the actual and
expected values to calculate the percent yield for the reaction. At this point, students
had several experiences with the mathematical aspects of the unit and were having
little difficulty. The main concern was that many groups were reporting more than
100 percent as their yield. This may have occurred because the students used a spoon
to stir that was removed when taking the mass readings and there may have been
some liquid clinging to the spoon which would make it appear that more carbon
dioxide was produced.
7. Air Bag Activity (Appendix D)

This activity was the least structured of all the activities in this unit. Students were
given a purpose, materials list, an unbalanced formula equation, and a goal of creating
an airbag that was neither over- nor under-inflated. They needed to balance the
equation for the reaction between vinegar (acetic acid) and baking soda (sodium
hydrogen carbonate), determine the volume of their plastic bag, determine how much
baking soda was needed to produce enough carbon dioxide to fill the bag, and
develop a procedure for inflating the bag. The students had most of the period to
complete the first part of the activity and have their procedure approved. In the
following lab period, the groups went into the lab to test their procedure and modify it
as needed. When they were satisfied with their results, they asked me to observe as
they completed the reaction. I then did a pinch test on the inflated bag to determine if

it was over-inflated, under-inflated, or perfectly inflated. Based on student responses

16

(see Results Section, Figure 11) to an anonymous Post-Unit Survey (Appendix C),
this may have been one of the most effective activities of the unit. Students worked
together and had good dialogue while completing the various tasks.

This activity was the most enjoyable for me and it was the activity most frequently
reported as being the student’s favorite. As the students began the lab, there was both
excitement and frustration over having to write their own procedure. Some students
were very detailed in how they thought it would be best to fill the bag with carbon
dioxide. Others felt that it was too hard to write their own procedure and spent a fair
amount of time complaining instead of working productively. By the time they
actually completed the reaction to fill the bag, the groups were all back on track and
working well. It was fun to watch as they tried to determine if their bag was inflated
properly and how they were going to modify their technique so that the bag inflated
to a level that I would judge as “just right.” For those groups whose bag did not earn
the “just right” label, I talked with them to see if they could give reasons why the bag
was either over- or under-inflated. Some groups said it was the bag as some bags
seemed to develop tiny holes in the seam after a couple of uses. Others said that they
did not seal the bag quickly enough. This was the one activity where students really
connected with the material and began to go beyond what I asked of them. Several
made a connection between the activity and the air bags found in automobiles which
caused them to ask if the chemicals we used were really in automotive air bags.
Rather than simply saying no, I responded with other questions that led them to

answer the question for themselves.

17

Assessments

During the unit students were given the following assessments:

1.

Pre- and Post-Unit Surveys (Appendix C)

These items were not graded because they were turned in anonymously.

Unit Pretest (Appendix B)

All students who submitted a Pretest that showed effort earned four points. Students

who did not submit a Pretest earned no points.

. Homework Problems

All homework assignments were graded on a four point scale based on the effort
shown by the student. A student who attempted all of the problems and showed work
would earn four points. A student who attempted more than half of the problems and
showed work would earn three points. A student who attempted half of the problems
and showed work would earn two points. A student who attempted less than half of
the problems and showed work would earn one point. A student who failed to submit
an assignment earned zero points.

Lab Activities (Appendix D)

Labs were graded similar to homework assignments, but were also scanned for
correctness of concepts in the extended response questions.

Quizzes and Unit Posttest (Appendix E)

Mathematical problems on quizzes and tests were graded based on having correct
work shown and an answer with an appropriate number of significant digits and

correct units.

18

RESULTS/EVALUATION

Pre-lPosttest Evaluation

For this unit, all students were given a Pretest and a Posttest (Appendix E) which
contained eleven common questions. The raw data for the students who submitted
completed consent forms are recorded in Appendix F. Two of the consenting students
did not return a pretest, so it was assumed that all questions were incorrectly answered.
For the remaining students, 25 of the remaining 32 improved their scores for those
questions. Of the 34 students, 27 passed the posttest with a score of 70 percent or better
(Appendix F). As is shown in Figure 1 below, there was improvement from pretest to

posttest for all but questions one, two, and ten.

 

Students with Comet Answers for Cannon Pretest and Posttets Items

('1 V Vt O I‘ w O‘ "“
l—I

Question

I Pretest
[J P0 sttest

Number of Students

     

 

 

 

Figure 1 — Student response scores for pretest & posttest questions

Questions one and two were about translating word equations into formula equations

which was a necessary skill for the stoichiometry unit, but this material was not taught or

re—taught during the unit. Questions three through five asked the students to write in the
correct coefficients to balance the given chemical equations. This skill was presented
two units prior which is the reason for the number of students who were able to
successfully answer those questions on the pretest. The skill was used frequently
throughout the unit which would account for more students being able to answer the
questions on the posttest. Question six asked students to describe coefficients in
chemical equations. This is another skill fiom a prior unit. Although it was not explicitly
re-taught during the unit, but student data show that there was more mastery of the
concept at the end of the unit. This is most likely because there was reinforcement of the
concept as students worked on the various assignments. Questions seven and eight asked
students to describe processes they learned in the two previous units that would be
needed in the stoichio metry unit. Questions nine through eleven asked students about
doing stoichiometric conversions, limiting reactants, and percent yield. These three skills
were all to be presented during the unit, so it was expected that students would have little
to no prior knowledge of the concepts involved. Numbers nine and eleven saw increases
in students being able to answer the questions by the end of the unit. Number ten saw a
decline of one student. I had expected an increase, so I am unsure if the problem is in the
way the question was worded as many of them were able to perform the calculations and

identify the limiting reactant in a later posttest question

Pre-lPost—Unit Survey Evaluation
Prior to the unit, students were asked to take a survey that included how they felt about

their abilities to do four types of conversions that were presented in the previous unit - 1)

20

grams to moles of a substance, 2) moles to grams of a substance, 3) liters to moles of a
substance, and 4) moles to liters of a substance (Appendix C). As seen in Figure 2, there
were just over half who responded that they felt that they could either usually or always

perform the conversions.

 

Pre-Ulit Abilities

 

 

 

 

 

 

 

 

 

 

 

 

Number of Student Responses

 

 

 

 

Type 1 Type 2 Type 3 Type 4

 

 

Figure 2 — How students perceived their ability to perform specific conversions from the
previous unit

By the end of the unit, students were exposed to more of these types of conversions and
more of them responded that they could either usually or always perform the conversions

(Figure 3).

21

 

 

 

 

 

Post-Urit Abilities

70

60
§
i:
s 50
g I Always
5 40 El Usually
g 30 I Sometimes
2 I Never
3 20
E

10

0

 

 

 

 

Figure 3 — How students perceived their ability to perform specific conversions fiom the
previous unit at the end of the stoichiometry unit

Based on post-unit data, most students felt that they could either usually or always
perform the seven types of stoichiometric calculations presented in the unit — 1) convert
from moles of one substance to moles of another substance, 2) convert from grams of one
substance to grams of another substance, 3) convert fi‘om grams of one substance to liters
of another substance, 4) convert from liters of one substance to grams of another
substance, 5) convert from liters of one substance to liters of another substance, 6)
determine which reactant is the limiting reactant, and 7) calculate percent yield (Figure

4).

22

 

 

 

 

 

 

Post-Urit Abilities

70
.. 60 '
3
i:
§ 50 .
g . I Always
S 40 I] Usually
g 30 , I Sometimes
E I Never
% 20
2

10

0
Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7

 

 

 

Figure 4 — How students perceived their ability to perform calculations presented during
the stoichiometry unit

The Pre-Unit Survey also asked students for information about their current attitudes
towards school and their post-graduation plans. Most (128 out of 132 respondents)
students indicated that they plan to continue their education past graduation from high

school and many (124 respondents) plan to attend a college or university to do so.

I also wanted to know how students felt about science classes and how they approached

things like studying, problem solving, or having trouble in a class. The survey results

suggest that science is not a popular subject at Lake Shore High School (Figure 5).

23

 

 

 

Students Favorite and Least Favorite Classes 'M‘m

60 D Science
2 5° ,
S. I English
3 40
El
'3 30 I Foreign Language
2
-°- 20
g History
z 10

0 I Other
. , (band, choir, business,
Favorite Class [east Favonte Class dental, art, dram, health)

 

 

 

 

Figure 5 — Students favorite and least favorite classes

The survey indicates that students find in class work to be the most helpful part of science

class and quizzes and tests to be the least helpful part (Figure 6).

 

Most and [cast Hellfirl Parts ofScience Class

 

I lecture/class
discussion/notes

El In-class work

I Homework

I labs

B Qu'mes/tests

Number of Student Repsonses

I Other
(science gums,
talking to teacherl

 

 

 

 

Most helpfirl part of Science class Least helpful part of Scbnce chss

 

 

Figure 6 — Student ranking of the most and least helpful parts of science classes

24

According to the survey data, the students’ number one choice for studying is in a quiet

place at home, but listening to music is a close second choice (Figure 7).

 

 

What do You do When You Study

60
i

50
§
0

ll 40
’5'.
we

3 30
m
"5

h 20
.8

g 10
Z

0

Listen to music Turn on tv for Go to a friend's Go to the public Find a quiet Other
background house library place at horn: (mike flash
noise cards, don't
study)

 

 

 

 

 

Figure 7 — What students do when they study

Based on survey results, the students have good problem solving skills — writing out

needed formulas, summarizing information, and drawing pictures (Figure 8).

25

 

 

How Do You Work on Story Problems

 

§ 100
:1
6
S 80
0
m
E 60
E
w 40
H—
e
h-
3 20
E
z 0
Haw pictures Sunnmrim Write formulas Ask teacher for Talk to Other
important that might be help classrmte (do work in
information needed head, try it
annd get it

 

 

checked, ask
parent)

Figure 8 — What strategies students use when working on story problems

 

Students indicated that they are most likely to talk to a friend when they have trouble in a

class (Figure 9).

 

What do You do When You Have Trouble in a Class

  

Number of Student Responses
N
o

 

 

15
10
5
0 l
Read the book Talk to the Talk to a friend Go back Ask questions Other i
teacher who has the through class in class (guess, do
class notes nothing) i
._J

 

 

Figure 9 — What strategies students use when they have problems in a class

26

At the end of the unit I wanted to know how the students felt about the various activities
they completed. I also thought it would be interesting to see which activity would be
their favorite. Personally, I liked all of the activities, but as I watched the students, I felt
as though they got the most out of the Airbag Activity. It was the activity where they
seemed the most involved and interested while they completed it. Figures 10 and 11

summarize their perceptions of the varying activities and which one they liked best.

 

Pos t-Ull't lab Attitllies

    

 

I Very Helpful
El Somewhat Helpful
I Not Hebful

 

 

Number of Student Responses
:3 5 8 8 8 e 8 a! 8

 

Al + Cucu Lab _ {if
of Baking Soda —

t.- 3: :1 no on>~
nae—a e-e '3 'gfi'g‘g -a 5.:
9'5: 5 ’4 “5.4% F a “3.;
See g :9 .53, a :2 s as
m .0 €9.75 E ._l o ’4

r2 9'4 a “an e-r

l-s 30>‘g a
Activity

 

 

 

Figure 10 -— How students felt about the activities they completed during the unit

27

 

Favorite Activity

 

Number of Student Responses
:3 ES 8 8 8 s 8 3 8

H r0 as a Q”
2:311 N cam—t «383 ram .0 an;
°3= a ”Os Frau we 3“” 5°
fiflm :1 fio— -— 8.36 ‘33 <
:2 o Due-3'3 93,-; git—7 3%
< ‘8
Activity

 

 

 

Figure 11 — Student rankings of the activities ficm the unit

Most of the students rated the activities either “somewhat helpful” or “very helpful.” The
lowest ratings came from the Stoichiometry Scavenger Hrmt. Although I liked the
Airbag Activity the best, I was surprised to see that so many students chose that as their
favorite. This was because there seemed to be more frustration with this activity than any

of the labs that had procedures in place for students to follow.

The open response section of the survey showed that students had a range of things to say
about the unit when it was finished. (All survey responses were anonymous.)

“It was a lot of math.”

“It’s too hard.”

“I need more help with it.”

“I think that the labs should be a little more spaced out. Instead of every

day, I think it should be every other day.”

28

“This was hard, but you taught it well.”

“This unit got better towards the end of the unit when I mostly understood

the material.”

“It was fim but hard. I learned a lot.”

“I love the math that is involved in this type of chemistry.”

“It was the easiest and I really understood it.”

“There isonethingandthatisthisisthe mostlhave learnedinaunita

while and I actually felt like I accomplished something.”

“This unit was the easiest for me so far, it was good to finally fully

understand everything I did. It made me more confident in the class.”
The comments about the unit being hard and having a lot of math are similar to previous
years. Although there were several comments written on the survey indicating that the
unit was difficult, it appears as though most students feel comfortable with the
calculations presented in the unit as there are fewer than fifteen “Never” responses to any
statements regarding the stoichiometric calculations (Figure 4). I generally do not get
many about the unit being the easiest or enjoying the unit. Those last few cements
made this entire process worthwhile as that was one of my goals — to get at least a few
students with an appreciation for how stoichiometry works. The students commenting on
the ease of the unit were likely to be students who responded either “Always” or

“Usually” to the statements regarding the stoichiometric calculations (Figure 4).

29

Activity Evaluation

Despite the amount of work students were asked to do in this unit, a majority of them
were able to complete the activities to a satisfactory level of three or four points on a four

point scale (Appendix F). The scores for the activities are summarized in Table 2.

Table 2 — Activity scores

 

 

 

 

 

 

 

 

Avtivity Rage of Scores Average Score ‘
Pretest 0 to 4 4
Scavenger Hunt 0 to 4 4
Al + CuCl2 Lab 0 to 4 3
Percent NaHCO3 in a Tablet Lab 0 to 4 3
Determination of Percent Yield Lab 0 to 4 3
Decomposition of Baking Soda Lab 0 to 4 3
Determining the Mass of C02 Lab 0 to 4 3
Airbag Activity 0 to 4 3

 

 

 

 

 

30

The first quiz of the unit (Appendix E) was a follow up to the Aluminum + Copper (II)
Chloride Lab (Appendix D). Students were given sample lab data to analyze and were
asked to answer questions similar to the ones on their lab. Many students (21 of 34) had
scores of 60% or less (Figure 12) which is likely because the required stoichiometry skills
were still new to them. Only one student was able to successfully answer all five

questions and earn 100%.

 

Al + CuClz Lab QuizScores

ssssssesé

Sco re (“/o)

5

 

O

 

~MnnaN<r¢nms~ss°9
'—"—"—' NVVV’VWWW

Stuchnt

 

 

Figure 12 — Student scores for Al + CuClz Lab Quiz

31

Stoichiometry Quiz #2 (Appendix E) saw an improvement in scores (Figure 13). More
than half of the students (19 of 34) were able to earn scores of 70% or better and eight
were able to earn a score of 100%. By this point, students had more time to work with

the various stoichiometric conversions.

 

StoichioImtry er'z #2 Scores

Sco re (“/o)

 

 

Student

 

 

Figure 13 — Student scores for Stoichiometry Quiz #2

32

Stoichiometry Quiz #3 (Appendix E) showed a drop in scores (Figure 14). Only eleven
of thirty-four students were able to achieve a score of 70% or better. This quiz
incorporated the concepts of limiting reactant and percent yield. Again, the concepts
were relatively new compared to the stoichiometric conversions that were presented on

the prior two quizzes. Despite the newness, two students were able to achieve perfect

SCOICS.

 

Stoichiometry Quiz #3 Scores

SCO re (o/o)

 

Student

 

 

 

Figure 14 — Student scores for Stoichiometry Quiz #3

33

Of the thirty-four students who participated in the study, only seven failed to achieve a
score of 70% or better (Figure 15) on the Stoichiometry Unit Test (Appendix E). The test
average for the participating students was 81% compared to an overall average of 75%
for the five sections of Chemistry. The greatest difficulties for the students were found in
the limiting reactant and percent yield questions. Most were able to accomplish the
stoichiometric conversions, but several had trouble incorporating the additional concepts.
Two students earned perfect scores and one student was able to earn a score of 107%.
The reasons for a student being able to earn more than 100% were because one question
(number 7) was a bit ambiguous in the wording and two questions (numbers 1 and 2)

were on topics that were not taught during the unit, so I counted them as extra credit

 

 

 

questions.
Posttest Scores

110

1(X)

90

80

,3, 70

E. 60

E 50

‘2 40

30

20

10

0
Sturbnt

 

 

Figure 15 - Student scores for Stoichiometry Unit Test

34

DISCUSSION AND CONCLUSION

At the start of the unit I asked students to complete the Pre-Unit Survey (Appendix C).
On average, the results were as I expected. Based on the comments I hear in class and in
the halls, it was no surprise that science would be ranked as the students’ least favorite
subject (Figure 5). What I did not expect was that fifty respondents would list rrrath as
their favorite subject (Figure 5). I also did not expect to see lecture and note taking
ranked as the second most helpful part of science class, especially since I often hear that
lecturing and note taking needs to be reduced in the classroom (Figure 6). I would have
expected that students would rank labs as a helpful part of class, but there seems to be
some debate on that as it was ranked third on the most helpful and least helpful lists
(Figure 6). I was also interested to see the results of what students do when they study
(Figure 7). The number of students who study with other noises in the room (music,
television, or fiiends) surpassed the number of those who say they need a quiet space
(Figure 7). I find that interesting because I often find that I need some sort of background
noise when I study. This leads me to question whether students would find it more
comfortable and conducive to learning if there is background noise in the classroom. The
student responses for how they attempt to work on story problems indicates tint they
have a good foundation for problem solving, but I often find that students have trouble
when assigned story-type problems in class (Figure 8). This leads me to question if they
are having trouble determining which information is important and which formulas might
be applicable seeing as summarizing and formula writing are the two most popular
strategies listed. I also thought it was noteworthy that the students ranked talking to a

teacher as fourth on the list of things to do when they have trouble in a class while talking

35

to a fiiend was their first choice (Figure 9). I understand that they are generally more
comfortable with talking to a peer. This makes me want to find ways to seem more
approachable to students as talking to classmates can sometimes backfire as that student

may unknowingly be passing on erroneous information and making the problem worse

instead of better.

My summer research resulted in a number of activities which were implemented this
year. However, this unit did not go quite as I expected when I was doing the research.
My initial thoughts were to edit the old labs that I felt were useful and add new ones. In
my attempt to include more activities to engage students, I think I may have gone too far
and tried to add too many activities. I quickly became overwhelmed with the work
involved in getting labs set up and broken down every day. I also worried about whether
I was trying to get the students to do too much in such a short time. I did not hear many
complaints, but I noticed that there was a decrease in the number of assignments being
submitted after the first few activities. To ease the problem, I eliminated the following
activities fiom the unit: Fizzy Drinks, S’more Stoichiometry, Making Chalk, and the
Balloon Lab (Appendix D). Many of the activities that were used involved the same
basic reaction of vinegar and baking soda. This is a reaction tint students often see in
science class in one of the lower grades, so there is a familiarity. This freed students
from being concerned about what kind of product they should get so they could
concentrate more on the task of analyzing the reaction to see how stoichiometric concepts

applied in each activity.

36

Looking back, I think that I would have tried to complete fewer labs, but take more time
to discuss results. Judging by student responses for the extended response questions on
the Post-Unit Survey (Appendix C), several of them agreed with me. The lab activities
that were attempted went mostly as planned. Some did not give the best results as far as

the data that the students generated, but that is always a possibility with any lab activity.

Even though I did not do as many activities as I initially planned, I feel that the activities
that we completed were useful. Students had more ownership of the concepts because
they were working with data they generated instead of worksheets that provided numbers
the students could not visualize. Many students commented during the unit that they
enjoyed doing the labs and the Post Unit Survey (Appendix C) indicated that they felt
that most of the labs were either somewhat helpful or very helpful (Figure 10). There
was an increase in the test average for this unit fi'om the 2004-2005 school year (69%) to
the 2006-2007 school year (75%). In addition, students were still able to remember some
of the activities from the unit as they completed their end of the year project. This project
asked students to build a torpedo-type boat from a plastic bottle then use their knowledge
of semester topics to create an adequate amount of carbon dioxide, from a reaction of
baking soda and vinegar, to propel the boat down a ten-foot section of rain gutter. A
large part of the project involved using stoichiometry to convert the desired amount of
carbon dioxide into starting amounts of baking soda and vinegar. I also noticed a slight
increase on the section of the final exam with the stoichiometry questions from the 2004-

2005 school year (75%) to the 2006-2007 school year (76%).

37

Next year, I plan to space out the labs for this unit a little better and eliminate or edit
some. I may eliminate the Stoichiometry Scavenger Hunt as I feel that the lab activities
reinforce the concepts better. This is likely because the students are working with the
chemicals instead of working with something that looks like it came fiom their textbook.
I will probably keep the Aluminum and Copper (11) chloride Lab, but change it so that
there is more time to discuss the required calculations as it is one of the first labs and the
students needed more support at that time. The Percent NaHC03 in a Tablet Lab is
another lab that I plan to keep because it was easy for the students to complete the
procedure and it gave expected results. The Determination of Percent Yield Lab is likely
to be eliminated because it did not give expected results and the required types of
calculations are repeated in other labs. I will keep the Decomposition of Baking Soda
Lab, but I think it might be usefiil to take a little more time introducing it and going over
the goal of the activity. If I keep the Determining the Mass of C02 Lab, it will need to be
edited as the results were not very good — many students had yields of more than 100%. I
think that could be solved by changing the procedure so that students take all mass
readings with the spoon in the beaker to see if they get results that are closer to 100%
yield without being over 100%. The Airbag Activity is one that will definitely be kept.
Although it fi'ustrates students to have to develop their own procedure, this activity
served multiple pmposes. Asking students to write their own procedure gives them
ownership in the activity and they express more satisfaction when they are finished. This
activity also gives students a foretaste of their final exam project and many of this year’s
students went back to it to assist in their thinking for the project. Some students read

through the introductory material for the carbon dioxide boats and almost immediately

38

mentioned that they had seen this information somewhere. After a little discussion with
their partners, several groups recognized that they were using the same materials as the
Airbag Activity and set out to find copies so they could write the balanced chemical
equation for baking soda and vinegar. For groups who made this connection, I noticed
that they were less fi'ustrated as they did not have to spend time searching for the
equation. This meant they could take more time determining how much carbon dioxide
they wanted then do the conversions to determine how much of the starting materials they

needed.

In the end, I was pleased with the overall results of the unit compared to previous years.
The students were more engaged in the learning process. There were more positive
comments about the unit. Students performed better both at the end of the unit and at the
end of the year. In addition, I enjoyed teaching more this year. The combination of these

things made this a worthwhile endeavor.

39

BIBLIOGRAPHY

Arasasingham, Ramesh D., Mare Taagepera, Frank Potter, Ingrid Marterell, and Stacy
Lenjers. “Asseessing the Effect of Web-Based Learning Tools in Student
Understanding of Stoichiometry Using Knowledge Space Theory.” Jeumal of
Chemical Education 82 (2005) 1251-1262

Bold, Christine. Supporting Learning and Teaching. London: David Fulton Publishers,
2004

Boyles, Nancy S. and Darlene Centadine. The Learning Differences Sourcebeok. Los
Angeles: Chicago NTC Contemporary, 1997

Dunn, Rita, and Kenneth Dunn. Teaching Students Through Their Individual Learning
Styles: a practical approach. Reston: Resten Publishing Company, Inc-Prentice
Hall, 1978

Dunn, Rita, and Shirley A. Griggs. Practical approaches to using learning styles in higher
education. Westpert: Bergin & Garvey, 2000

Hassard, Jack. The Art of Teaching Scimrce: Inquiry and Innovation in Middle School
and High School. New York: Oxford University Press (US), 2005

Herrerr, J. Dudley. The Chemistry Clas_sreom: Formulas for Successful Teachng.
Washingterr, DC: American Chemical Society, 1996

Huddle, P. A. and A. E. Pillay. “An In-Depth Study of Misconceptions in Stoichiometry
and Chemical Equilibrium at a South African University.” Journal of Research in
Science Teaching 33 (1996): 65-78

Jensen, Eric. Teaching with the Brain in Mind. 2MI ed. Alexandria: Association for
Supervision and Curriculum Development, 2005

Jeen, Kyungmeen, Douglas Huffman, and Taehee Neh. “The Effects of Thinking Aloud
Pair Problem Solving on High School Students’ Chemistry Problem-Solving
Performance and Verbal Interactions.” Journal of Chemical Educgtien 82 (2005):
1558-1564

Koch, Hehnut. “Simplifying Stoichiometry.” The Science Teacher 62 (1995) 36-39

Lawrence, Gordon. People Types & Tiger Stripes. 2"‘1 ed. Gainesville: Center for
Applications of Psychological Type, Inc., 1984

Poole, Richard L. “Teaching Stoichiometry: a Two Cycle Approach.” Journal of
Chemical Education 66 (1989): 57-58

40

Reiff, Judith C. Learning Sgles. Washington, DC: Professional Library, National
Education Association, 1992

Sternberg, Robert J. and Li-fang Zhang. Persp_ectives on Thinking Learning, and
Cognitive Styles. Educational Psychology Series. Mahwah: Lawrence Erlbaum
Associates, 2000

Sumrall, William J. “Silver Science.” The Science Teacher; 58.9 (1991): 36-39

Zemelman, Steven, Harvey Daniels, and Arthur Hyde. Best Pjractice: Todpy’s Standards
for Teacng Learning in America’s Schools. 3lrd ed. Portsmouth: Heinemann—
Reed Elsevier, 2005

41

APPENDICES

42

APPENDIX A - UNIT OUTLINES

43

Proposed outline of activities from research summer

 

Day

Topic/activity

Text
section

Homework

Notes

 

Stoichiometry Pretest & Survey
Mg + HCl demonstration

What is Stoichiometry
Beginning Stoichiometry
Problems (mole-mole)

9.1, 9.2

Mole-mole worksheet

 

Types of Stoichiometry
Problems

Stoichiometry
worksheets

 

Stoichiometry Scavenger Hunt

 

Percent NaHCO3 in a Tablet Lab

 

mgg

Stoichiometry Quiz #1
Al + Cqu Lab

 

Z

Discover It Demonstration
Limiting Reactants & Percent
Yield

9.3

Cookie steich
worksheet — baking

optional

 

Post-hb Quiz - Cu + AgNO;
Lab

Fizzy Drinks

S’more Stoichiometry Activity

 

Decomposition of Baking Soda

 

51$

Stoichiometry Quiz #2
Determining Mass of C02 Lab

 

'1']

Determination of Percent Yield
Lab

 

Making Chalk Lab

 

g]:

Stoichiometry Quiz #3
Balloon Lab

 

Air Bag Activity

 

Review

 

 

mgg

 

Stoichiometgy test

 

 

 

 

44

 

Outline of activities as presented in class

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Date Topic/Activity Text Homework Notes
Section
3/19 What is Stoichiometry 9.1, 9.2 Mole-mole worksheet
Beginning Stoichiometry
Problems (mole-mole)
3/20 Types of Stoichiometry Stoichiometry
Problems worksheets
3/21 Stoichiomegy Scavenger Hunt
3/22 Al + Cqu Lab 1/2 day - PT
conferences
3/23 Post-lab Quiz — Cu + AgNO3 9.3
Lab
Limiting Reactants & Percent
Yield
3/26 Percent NaHCO3 in a Tablet Lab
3/27 Stoichiometry Quiz #2
Determination of Percent Yield
Lab
3/28 Decomposition of Baking Soda
Lab
3/29 Determining Mass of C02 Lab
3/30 Stoichiometry Quiz #3
Air Bag Activity (part 1)
4/2 Air Bag Activity (part II)
4/3 Review
4/4 Stoichiometry test
4/5 Post-Unit Survey Get consent form 1/2 day

 

 

 

signed

 

 

45

 

APPENDIX B - CONSENT FORM

46

Improving Student Comprehension of Stoichiometric Concepts
Parent Consent and Student Assent Form

I am currently enrolled as a graduate student in Michigan State University’s Department
of Science and Mathematics Education (DSME). My thesis research is on improving
student comprehension of stoichiometric concepts (which are the mathematics of
chemical equations). Some corrrpenents of the unit are determining the amount of
product that can be formed in a reaction and determining percent yield of the reaction or
how much of the expected amount was obtained in an experiment.

Data for the study will be collected from standard student work generated in the course of
teaching this unit such as pre and post tests, lab activities, quizzes, and surveys. I am
asking for your perrrrissien to include your child’s data in my thesis. Your child’s
privacy is a foremost cencem. During the study, I will collect and copy student work.
These assignments will have the student’s name removed prior to use in the study. All of
the work being collected will be stored in a locked cabinet until my thesis is finished and
will be shredded after that time. In addition, your child’s identity will not be attached any
data in my thesis paper or in any images used in the thesis presentation. Your child’s
privacy will be protected to the maximum extent allowable by law.

Participation in the study is completely voluntary. Students who do not participate in the
study will not be penalized in any way. Students who do not participate in the study will
still be expected to participate in class and complete assignments. Students who
participate in the study will not be given extra work to complete. You may request that
your child’s information not be included in this study at any time and your request will be
honored. There are no known risks associated with participating in this study.
Participation in this study may contribute to determining the best way to present
stoichiometric concepts to high school students.

47

If you are willing to allow your child to participate in the study, please complete the
attached form and return it to me by February 28‘”, 2007. Please seal it in the provided
envelope with your child’s name on the outside of the envelope. The envelopes will be
stored in a locked cabinet and opened after the unit is completed. Any work fiom a
student who is not to be included in the study will be shredded.

If you have any questions about the study, please contact me by e-mail at
CKemner@lsps.org or by phone at (586) 385-8896. Questions about the study may also
be directed to Dr. Merle Heidemann at the DSME by e-mail at heidema2@msu.edu, by
phone at (517) 432—2152, or by mail at 118 North Kedzie, East Lansing, Michigan 48824.
If you have any questions or concerns regarding your rights as a study participant, or are
dissatisfied at any time with any aspect of this study, you may contact - anonymously, if
you wish - Peter Vasilenko, Ph.D., Director of the Human Subject Protection Programs at
Michigan State University, by phone at (517) 355-2180, by e-rrrail at irb@msu.edu, by
fax at (517) 432-4503, or by mail at 202 Olds Hall, East Lansing, MI 48824.

Thank you,

Mrs. Connie Kemner
Chemistry Teacher
Lake Shore High School

48

I voluntarily agree to allow to participate in this
study.
(print student name)

Please check all that apply.

I give Mrs. Kemner permission to use data generated from my child’s work in
chemistry class to be used in the thesis project. All data from my child will 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 participation in the
study.

I give Mrs. Kemner permission to use pictures of my child during her work on
this thesis project. My child will not be identified in these pictures.

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

 

 

(Parent/Guardian signature) (date)

I voluntarily agree to participate in this thesis project.

 

 

(Student signature) (date)

49

APPENDIX C - SURVEYS

50

Stoichiometry: Pre—Unit Survey

Circle the answer that fits you best. You are not required to put your name on this
assignment.

1)

2)

3)

4)

5)

6)

7)

3)

9)

Do you plan to continue your education after graduating from Lake Shore?
Yes No Not sure

If you answered yes to the previous question, please indicate where you will continue
your education.

College/University Trade School

Military On-the-job training/ Apprenticeship

If you plan to continue your education, will you need to take another chemistry
course?

Yes No Not sure

Do you plan to have a career that is related to science?

Yes No Not sure

If you answered yes to the previous question, please list what career you are

considering.

 

 

My favorite class is

Math Science English Foreign Language
History/Social Studies Other (please list which one)

My least favorite class is

Math Science English Foreign Language
History/Social Studies Other (please list which one)

My usual grade in math classes is

A B C D F

My usual grade in science classes is

A B C D F

10) When you have trouble in a class, what do you do? Please number your choices with

1 being the first thing you do and 6 being the last thing you would try.

__ Read the book __ Talk to the teacher

__ Talk to a friend who has the class _ Go back through the class notes
__ Ask questions in class

__ Other (please describe)

 

51

11)When you study, which of the following do you do? Please number your choices
with 1 being the thing you are most likely to do and 6 being the thing you are least

 

likely to do.
__ Listen to music __ Turn on the tv for background noise
__ Go to a friend’s house _ Go to the public library
_ Find a room in the house that is quiet
_ Other (please describe)
12) When you are assigned story problems, do you do any of the following? Circle all
that apply.
Draw pictures Summarize the important information

Write formulas that might be needed Ask the teacher for help
Discuss the problem with someone else in the class

 

 

 

 

Other (please describe)

13) Which part of science class is most helpful to you?
Lecture/Class discussion In-class work
Homework Labs
Quizzes/Tests Other (please describe)

14) Which part of science class is least helpful to you?
Lecture/Class discussion In-class work
Homework Labs
Quizzes/Tests Other (please describe)

15) What is your favorite part of science class?
Lecture/Class discussion In-class work
Homework Labs
Quizzes/Tests Other (please describe)

16) What is your least favorite part of science class?
Lecture/Class discussion In-class work
Homework Labs
Quizzes/Tests Other (please describe)

 

17) Please shade the box that most fits how you feel.

 

 

I can convert from grams of a

 

substance to moles of the same Always Usually Sometimes Never
substance.

I can convert fi'om moles of a

substance to grams of the same Alvvays Usually Sometimes Never
substance.

 

I can convert from liters of a
substance to moles of a Always Usually Sometimes Never
substance.

I can convert from moles of a
substance to liters of a substance.

 

 

 

 

 

 

Always Usually Sometimes Never

 

52

Stoichiometry: Post-Unit Survey

Answer each of the following questions. You are not required to put your name on this
assignment.

1) Please shade the box that most fits how you feel.

 

I can convert from grams
of a substance to moles of
the same substance.

Always

Usually

Sometimes

Never

 

I can convert fi'om moles
of a substance to grams of
the same substance.

Always

Usually

Sometimes

Never

 

I can convert from liters of
a substance to moles of a
substance.

Always

Usually

Sometimes

Never

 

I can convert fiom moles
of a substance to liters of a
substance.

Always

Usually

Sometimes

Never

 

I can convert from moles
of one substance to moles
of another substance.

Always

Usually

Sometimes

Never

 

I can convert from grams
of one substance to grams
of another substance.

Always

Usually

Sometimes

Never

 

I can convert fiom grams
of one substance to liters
of another substance.

Always

Usually

Sometimes

Never

 

I can convert fi'om liters of
one substance to grams of
another substance.

Always

Usually

Sometimes

Never

 

I can convert from liters of
one substance to liters of
another substance.

Always

Usually

Sometimes

Never

 

I can determine which
reactant is the limiting
reactant.

Always

Usually

Sometimes

Never

 

 

I can calculate percent
yield.

 

Always

 

Usually

 

Sometimes

 

Never

 

53

 

2) Rate the activities and labs from this unit by shading the box that rrrost fits how you

 

 

 

 

 

 

 

 

 

 

 

 

 

feel.
. . . Somewhat
Arr Bag Actrvrty Very Helpful Helpful Not Helpful
Somewhat
Al + CuClz Lab Very Helpful Helpful Not Helpful
Somewhat
Balloon Lab Very Helpful Helpful Not Helpful
Decomposition of Baking Soda Very Helpful 83:122.]? Not Helpful
Determination of Percent Yield Somewhat
Lab Very Helpful Helpful Not Helpful
Determining Mass of C02 Lab Very Helpful S‘Huellejii‘iii‘t Not Helpful
Discover It (Paper Clip) Activity Very Helpful Satfgzrt Not Helpful
. . Somewhat
F rzzy Drinks Very Helpful Helpful Not Helpful
. Somewhat
Making Chalk Lab Very Helpful Helpful Not Helpful
Percent NaHCO; in a Tablet Lab Very Helpful 81:33:? Not Helpful
S’more Stoichiometry Activity Very Helpful S;";f;;:rt Not Helpful
Stoichiometry Scavenger Hunt Very Helpful 83:31.3? Not Helpful

 

 

 

 

describe why you liked it best.

54

4) Is there anything else about this unit that you would like to say?

3) From the list of activities/labs in the previous question, select your favorite and

 

APPENDIX D - ACTIVITIES

55

Stoichiometry Scavenger Hunt
Adapted fi’om: http://nwnv2. gsu.edu/~mst irh/steichiometryht ml

Name: Partner(s):

 

Please visit the listed websites, follow the directions, and answer the questions. In order
to earn credit for the assignment, you must show all work (using the method shown in
class) for mathematical problems on a separate sheet of paper.

 

Website #1:
http://dbhswvusdk l 2.ca.us/webdocs/Stoichiometry/Stoichiometry html

1) Read "What is stoichiometry?"
a) What does the word stoichiometry mean?

b) In your words, why are stoichiometric calculations important?

0) To whom might stoichiometric calculations be important?

2) Read the following sections:
a) Molar Ratios
b) Given Moles, Get Moles
c) Given Grams, Get Moles and Given Moles, Get Grams
d) Given Grams, Get Grams

56

3) Go to Stoichiometric Problems (found at
http://dbhswvusdkl2.0a.us/webdocs/Stoichiometry/Stoichiometry-Worksheet.html)
a) De 1a,1b, 2, 3, 4

 

The answers are provided on this site; use them to check your answers only. Keep in
mind you MUST show your work to earn credit.

 

Website #2:
http://library.kcc.hawaii.edu/extemal/chemistry/everyday_combustion. html

1) Read the information on fuels and answer the following questions.
a) Fuels such as gasoline, propane, diesel, etc. primarily consist of what two
elements?

b) What is the molar ratio of C3I‘I3 to water?

c) If 4 moles of C3H3 reacted according to the reaction given for propane, how many
moles of carbon dioxide would result?

(1) How many grams of water would be produced if an initial amount of 50.0 g of
oxygen gas reacted with unlimited amounts of C3H8?

57

Stoichiometry Manipulatives

     

tube connected by a
dowel rod with fun foam and plastic conversion panels, segments labels are “Grams of A
Given,” “1 Mole of A/Molar Mass of A,” “# moles B in Chem. Eq./# moles A in Chem.
Eq.,” and “Volume of B/l Mole of B” respectively)

Figure 16 — Manipulative, first version (segments of a mailing

Bela: Mu
M I

 

Figure 17 — Manipulative, second version (a whole mailing tube covered in construction
paper with fun foam bands containing conversion panels attached by clear contact paper,
segments labels are “Grams of A Given,” “1 Mole of A/Molar Mass of A,” “# moles B in
Chem. Eq./# moles A in Chem. Eq.,” and “Molar Mass of B/l Mole of B” respectively)

58

1)
2)
3)
4)

1)
2)

3)

Teacher Demonstrations
Mg + HCl

Adapted fi'om Addison-Wesley’s Chemistry (© 2000, page 241)
Determine the mass of a magnesium strip (about 2.5-3.5 cm in length).
Pour 50 mL ofl M HCl into a 100 mL beaker.
Put the Mg strip into the beaker and ask students to observe the reaction.
Student questions:
a) Write a balanced equation for the observed reaction.
b) Interpret the equation (explain the coefficients) in terms of moles, mass, and
particles.

Discover It
Adapted from Addison-Wesley’s Chemistry (© 2000, page 236)

Have a bag with 20 metal paper clips (symbol M) and 20 plastic-coated paper clips of

a single color (symbol C) availble for this activity.

Ask a student to assist by completing the following directions.

a) Pour the paper clips out on your desktop.

b) Join pairs of matching paper clips to make diatomic molecules of each reactant
(M and C). Put the completed molecules back into the bag.

c) Without looking at the molecules, take out 15 molecules from the bag.

(1) Line up the M2 and C2 molecules in two adjacent, vertical columns.

e) Pair up the reactant molecules in the 1:3 M2 to C2 ratio as shown in the equation
of M2 + 3 C2 —> 2 MC3. (Students might do better if they have a visual
representation on the board of what is expected in this step.)

i) Make the molecules “react” by taking them apart and forming product molecules.

Student questions:

a) How many reactant molecules of each type were drawn from the bag?

b) How many molecules of the product were able to be formed?

c) Which reactant molecule did you run out of first?

d) How many reactant molecules were left over after the reaction and what type
were they?

***T'his could be used as a class activity instead by giving bags to groups and comparing
data from the groups at the end of the activity.

59

Acid & Marble Chip Demo

Adapted from Holt’s Chemistry: Visualizing Matter (0 2000, pages 367-368)

~15 minutes

Place a Petri dish on the overhead projector and add 1 M HCl until the dish is half
full. Record reactant formula on the board.

Have a student to determine the mass of 5-10 marble chips to the nearest thousandth
of a gram. Record reactant formula on the board along with the mass.

Add the marble chips to the Petri dish.

Student questions:

1)
2)

3)
4)

Safety:

3)
b)

c)

d)

g)

What gas is in the bubbles being generated? C02

How do you know the reaction is done? No more bubbles are generated

Look at what’s left in the Petri dish.

i) What is the excess reactant? Probably CaC03

it) What is the limiting reactant? Whatever is used up, probably HCI

How could you find the theoretical yield of CO2? Dry the marble chips, get the
new mass, use stoichiometry to convert from grams of marble to grams of
carbon dioxide

How could you find the actual yield of CO2? Do the reaction again & collect the
gas being generated

How could you find the percent yield of CO2? Divide the actual yield by the
theoretical yield and multiply by 100

How does this demonstration show the effect of acid rain on marble? Acid causes
damage to the marble - this explains some of the destruction of marble
monuments

Wear goggles. Keep students 3 or more meters from the reaction. Avoid getting acid on
your skin. Avoid breathing the acid fiimes

DiSposal:

Decant the liquid and wash any remaining chips with distilled water. Place the wash
water with the lefiover reaction liquid. Test the pH of the solution. If it is 3 or less,
neutralize it with 1 M NaOH and pour the liquid down the drain with plenty of water.
Save the chips for a future use.

60

Aluminum + Copper (II) Chloride Stoichiometry Lab

Adapted from: h_ttp:l/dcpanmcntsexy.cdu/tops/Stoichiomctry/stoichstudcnt.htm

Purpose

Determine the stoichiometric relationship of two reactants.

Materials

0 Aluminum wire 0 Wash bottle with 0 Filter paper

0 Electronic balance distilled water a Funnel

a CuCl2 a 2 H20 0 Tweezers o 250 mL beaker
- Screw-top test tube 0 Paper towel

Procedure

All masses need to be recorded to the nearest 0. 01 g.

D91 1

1) Loosely coil a small piece (between 5.0 and 10.0 cm) of Al wire around a pencil.

2)
3)

4)

5)

6)
7)

8)

9)

Remember that your coil needs to fit into the test tube. Determine the mass of the
wire coil.

Determine the mass of your test tube and lid.

Place a pea-sized amount of CuCl2 - 2 H2O in your test tube, reseal it, and determine
the mass.

Use your wash bottle to add the water to the test tube. Add enough water to fill the
tube to the 5 or 6 mL line. Make sure the cap is on tight and shake the tube to make
sure the solid is completely dissolved. If there is still solid left in the test tube you
may, add another milliliter of distilled water. Record the color of the solution. (It
may help to put the test tube on a piece of white paper to see the color.)

Place the wire into the CuCl2 solution, replace the cap, and shake gently. Observe the
reaction for 10 minutes, occasionally shaking gently to remove Cu crystals from the
Wire.

Take a small piece of paper towel and a filter paper. Use a pencil to put the initials of
your group members on both items. Determine the mass of the filter paper.

Fold the filter paper to fit into your fiinnel. Place the filter paper and fimnel into a
250 mL beaker.

Empty contents of test tube into the filter paper. (Make sure the liquid does not reach
the top of the filter or you may lose some of your product.) Use the tweezers to pull
the wire out of the filter. Use the wash bottle to rinse any remaining copper fiom the
wire into the filter. Put the wire on the paper towel and place it in the area indicated
by your instructor.

Use the wash bottle to rinse any remaining copper fiom the test tube into the filter.
Record the color of the final solution in the beaker. (It may help to put the beaker on
a piece of white paper to see the color.)

10) When all of the liquid is out of the filter paper, carefully remove the filter, unfold it,

and place it on the paper towel with your wire.

1 1) Clean up and put away all materials.

61

Day 2

1) Determine the mass of the wire. Return the wire to your instructor.

2) Determine the mass of your dried filter paper and crystals. Record your data.
3) Clean up and put away all materials.

Data Table

 

Initial mass of Al wire

 

Mass of CuCl2

 

Color of CuCl2 solution before reaction

 

Color of solution at end of reaction

 

Final mass of AI wire

 

Mass of filter paper

 

Mass of filter paper + Cu crystals

 

 

 

 

Questions
Answer the following questions on a separate sheet of paper. You must show your
work to earn credit for the questions involving calculations.
1) Use the information from your data table to calculate:
a) the mass of Al reacted. c) the mass of Cu crystals
b) the mass of CuCl2 - 2 H2O in
solution.

2) Use the information fiom Question 1 to determine:
a) the moles of Al reacted. b) the moles of CuCl2 reacted.
c) the moles of Cu crystals produced.
(***Remember to convert mass of
CuCl2 o 2 H2O to moles of CuCl2 o 2 H20
and moles of CuCl2 o 2 H20 to moles of CuCl2)

3) Write the mole ratio:
a) of Cu to Al. b) of Cu to CuCl2.

4) Write the balanced equation for the single-replacement reaction of A1 with CuCl2.

5) According to the balanced chemical reaction in Question 4, what is the mole ratio of
Cu produced to Al reacted?

62

6) How does the Cu to Al mole ratio in Question 5 compare with the mole ratio
determined in Question 3? If it did not match, discuss what might have happened in
the lab that would change the mole ratio. (Be specific.)

7) What happened to the color of the solution as the reaction took place? If it changed
colors, suggest one reason why this would lmppen.

63

Percent NaHCO3 in a Tablet

Adapted from: http://wwmvcmsk l 2.nc.us/allschools/providc ncc/keenan/chcm/labs/nahco3 . pdf

Purpose
Determine the percent of NaHCO; by mass in an effervescent tablet (e. g., Alka Seltzer).

Background Information

Effervescent tablets (vitamin tablets, lemonade, etc.) contain sugar, flavoring, and food
coloring as well as tartaric acid and sodium bicarbonate. When such a tablet is added to
water, the sodium bicarbonate reacts with the tartaric acid to form sodium tartrate, carbon
dioxide and water. The sodium bicarbonate content of the tablet can be experimentally
determined fi'om the amount of carbon dioxide generated.

Materials

0 Balance 0 Watch glass 0 Balance paper or
0 Graduated cylinder 0 Stirring rod weigh boat

0 125 mL beaker o Effervescent tablet
Procedure

Record all experimental data in the given data table. Record masses to the nearest 0. 01

g.

1) Add approximately 50 mL water to the beaker using a graduated cylinder. Find the
mass of the beaker, watch glass, stirring rod, and water. Record your data.

2) Tare a piece of clean paper or weigh boat. Add the tablet to the balance. Record your
data. Do not place the tablet directly on the balance pan!

3) Add the tablet to the water and cover immediately with the watch glass. Let it react.
When the fizzing has subsided somewhat, stir (with a glass stirring rod) to increase
the rate of the reaction. You want to remove as much CO2 as possible. Be carefiil not
to lose any of the water that has accumulated on the underside of the watch glass. Do
NOT place the watch glass down on the counter top or on a paper towel.

4) Remass the beaker, stirring rod, watch glass, and water solution. Record your data.

5) Record your Trial 1 data on the board.

6) Copy two other columns of data to complete your data table.

Data Table

 

Trial 1 Trial 2 Trial 3

 

Mass of beaker, stirring rod, watch glass and 50
mL water (before reaction)

 

Mass of effervescent tablet (before reaction)

 

Mass of beaker, stirring rod, watchglass, 50 mL
water and tablet (before reaction)

 

Mass of beaker, stirring rod, watchglass, 50 mL
water and tablet (after reaction)

 

Mass of CO2 emitted

 

Calculated mass of NaHCO; in original tablet

 

Percent NaHCO; in original tablet

 

Theoretical mass of NaHCO; in tablet

 

Error, g

 

 

 

 

 

Relative error, %

 

Questions
You must show your work on a separate sheet of paper to earn credit for the
calculations. Record your final answers in the data table.
1) Balance the equation.

_ NaHCO3 + _ H6C4O6 —) _ N32C4H406 + _ C02 + _ H20

2) Calculate the mass of the CO2 generated.
3) Using stoichiometry, calculate the mass of NaHCO; in the tablet.
4) Calculate the percent by mass of NaHCO; that was in the tablet prior to the reaction.

5) Check the package to find the mass of NaHCO3 that is in each tablet. Record the
data.

6) Calculate your error in grams.
Error = Measured Amount — Theoretical Amount

7) Calculate the percent error.
% error = [ (Measured Amount — Theoretical Amount)/ Theoretical Amount] X 100

8) Discuss potential reasons for error in this lab. (Be specific.)

65

 

Determination of Percent Yield
Adapted from:
hug/Anvwcmskl2_nc.us/allschools/providcncc/kccnan/chem/labs/dctn of percent yieldpdf

Purpose
Determine the theoretical and experimental yields of NaCl and calculate the percent
yield.

Materiab

0 250 mL beaker o 1 M HCl solution 0 Hot plate
0 Balance 0 50 mL beaker

o NaHCO3 o Pipette

Procedure

Record all experimental data in the given data table. Record masses to the nearest 0. 01

g.

1) Mass the 250 mL beaker. Record your data.

2) Mass no more than 0.50 grams of NaHCO3 into the beaker. Record the exact amount
being used.

3) Put approximately 25 mL of l M HCl into the 50 mL beaker.

4) Use a pipette to slowly add 10 drops of HCl to the NaHCO3. Gently swirl the liquid
to thoroughly mix the acid into the NaHCOg.

5) Repeat the previous step until no bubbles form while swirling the beaker.

6) Place the beaker on the hot plate and heat it for about 15 minutes or until it seems that
all of the water is gone from the beaker. Do not turn the hot plate higher than setting
3. (While you wait for the water to evaporate, start working on the Questions. Work
in the lab area so that you can continue to monitor your experiment.)

7) After heating on level 3 for 15 minutes, turn the setting to level 1 and heat for another
5-10 minutes to ensure that all water is gone from the beaker.

8) Cool the beaker for 5 minutes. Do this by placing a piece of paper towel on the
counter and set the beaker on the towel.

9) When the beaker is cool, mass the beaker and product. Record your data.

10) Clean up your lab area.

11) Record your Trial 1 data on the board.

12) Copy two other columns of data to complete your data table.

13) Finish answering the questions.

66

Data Table

 

Trial 1 Trial 2 Trial 3

 

Mass of beaker

 

Mass of beaker and NaHCO;

 

Mass of NaHCO;

 

Mass of beaker, watch glass and product

 

Mass of product (actual yield)

 

Theoretical yield of NaCl (calculated)

 

 

 

 

 

 

Percent yield of NaCl

 

Questions

You must show your work to earn credit for the calculations. Record your final
answers in the data table.

1) Calculate the mass of NaHCO3 used in this experiment.

2) The equation for the reaction is as follows. If it is not balanced, you need to balance
it before going to the next question. If it is balanced, please indicate that by putting a
large check mark to the left of the equation.

_ NaHCO3 + _ HCl —) _ NaCl + _ H2O + __ C02

3) Calculate the actual yield of product.

4) Use stoichiometry to calculate the theoretical yield of NaCl starting with your mass of
NaHCO;;.

5) Calculate the percent yield of NaCl.

6) If your percent yield was not 100%, give one reason why this may have happened.
Be specific.

67

Kitchen Stoichiometry

Adapted from: ht t p:// ichcmcd.chemwiscedu/J oumal/lssucs/2000/Dec/ PlusSub/V 7 7N l 2/p l 608 Aidf

Background

Stoichiometry is the mathematics of chemical equations. This concept also applies to
recipes. Just as there is a correct ratio of reactants to get a desired set of products, there is
a correct ratio of ingredients to get a desired finished product. In this lab, you will use
pre-sweetened powered drink mix, citric acid, baking soda, and water to create a
carbonated beverage.

Materials

0 5 medium cups 0 Distilled water 0 Baking soda (NaHCO3)
o 2-3 small cups 0 Coffee stirrer or straw 0 Balance

0 V2 tsp measuring spoon o 2 paper mufi'm cups

0 '/2 cup measuring cup 0 Citric acid (H3C6HsO7)

Procedure

1) Use a marker to label your medium cups A through E.

2) Measure 1 '/2 tsp of drink mix and put it into cup A. Repeat for cups B through E.

3) Add ‘/2 cup of water to cup A. Use the coffee stirrer to mix the ingredients. Pour

4)

5)

6)

7)

8)

9)

small samples for each group member. Taste the beverage and record your
observations. Keep the rest of the beverage in cup A as a control when you sample
the other trials.

Label 3 muffm cup “citric acid.” Find the mass of this cup and record the value. Use
the balance and the “citric acid” cup, measure approximately 0.50 grams of citric
acid. Add the citric acid to cup B.

Add ‘/2 cup of water to cup B. Use the coffee stirrer to mix the ingredients. Pour
small samples for each group member. Taste a very small amount of the beverage
and record your observations. Pour the remaining beverage into the sink and discard
cup B.

Label a muffin cup “baking soda.” Find the mass of this cup and record the value.
Use the balance and the “baking soda” cup, measure approximately 0.50 grams of
baking soda. Add the baking soda to cup C.

Add 1/2 cup of water to cup C. Use the coffee stirrer to mix the ingredients. Pour
small samples for each group member. Taste a very small amount of the beverage
and record your observations. Pour the remaining beverage into the sink and discard
cup C.

Using the appropriate muffm cups and the balance, measure no more than 0.50 grams
of baking soda and citric acid. Add the baking soda and citric acid to cup D.

Add 1/2 cup of water to cup D. Use the coffee stirrer to mix the ingredients. Pour
small samples for each group member. Taste a very small amount of the beverage
and record your observations. Pour the remaining beverage into the sink and discard
cup D.

10) Balance the chemical equation for the reaction between citric acid and baking soda.

H3C5H507 (aq) + _ NaHC03 (aq) _.) _ Na3C6H507 (aq) + _ H200) + _ C02 (3)

68

ll)Use stoichiometry to determine how much citric acid is required to react completely
with 0.50 grams of baking soda. Show your work to your instructor and ask the
instructor to initial your lab sheet before completing the next step.

12) Measure 0.50 grams of baking soda and the amount of citric acid from the previous
step using the balance and the appropriate muffin cups. Add the baking soda and
citric acid to cup E.

l3)Add 1/2 cup of water to cup E. Use the coffee stirrer to mix the ingredients. Pour
small samples for each group member. Taste the beverage and record your
observations. Compare the results of cup E to the results of Cup A.

14) Clean your lab area. Pour any remaining liquid into the sink. Discard the cups,
coffee stirrers, and muffm cups.

 

 

 

 

 

 

 

 

 

 

 

 

Data Table
Total
Total amount of
amount of baking
Cup citric acid soda Taste of beverage
A
B
C
D
E
Questions

Answer the following questions on a separate sheet of paper. You must show your
work to earn credit for the questions involving calculations.
1) Show your work for the amount of citric acid needed in cup E.

Instructor’s initials
2) Why do citric acid and baking soda not react until water is added?

 

3) Why is fizzing observed in cup C?

4) How will the drink taste if too much citric acid is used? How it taste if too much
baking soda is used?

5) F izzies drink tablets use the reaction you performed in class to rmke carbonated
beverages when added to water. Why do the tablets use aspartame sweetener instead
of sugar?

6) What are some other practical uses of stoichiometry?

69

The Stoichiometry of S’mores
Adapted fiom: http://dcvacaf.caes.uga.edu/main/lcssonPlarr/SMorcLdef

Introduction
In this activity, you will explore the principles of stoichiometry by building S’mores.

Materials

0 Chocolate bar (C2) 0 Paper plate

0 Marshmallows (M) o Napkins

0 Whole graham crackers (G2) 0 Electronic balance
Procedure

Record all experimental data in the given data table. Record masses to the nearest 0.01 g.
1) Mass one of each reactant - one chocolate square, one marshmallow, and one graham
cracker square. Use a napkin to keep your food items fiom touching the balance.

2) Perform a synthesis reaction and form a S’more. Keep all edible items on the plate.

Write the balanced equation for the reaction below. Use following symbols for each
reactant: C = chocolate square, M = rmrshmallow, and G = graham cracker.

3) Cause the reaction to go to completion by forming as many of the products as you
possibly can. Mass and record ONE of the representative products (one S’more).

4) Count the number of products you were able to form.

Data Table

 

Mass of chocolate square (C)

 

Mass of marshmallow (M)

 

Mass of graham cracker square (G)

 

Mass of one completed S’more

 

Number of completed S’mores

 

Number of left over chocolate pieces

 

Number of left over marshmallows

 

 

 

 

Number of left over graham crackers

 

7O

Questions

Answer each of the following questions in complete sentences.

1) Is there a relationship between the mass of a S’more and the masses of the reactants
used to make it? If so, what is the relationship? What law have you studied in this
course that might define this relationship?

2) A limiting reactant is the material responsible for a reaction reaching completion. In
the reaction, what was the limiting reactant?

3) What reactants, if any, were left after building as many whole S’mores as possible?

71

Decomposition of Baking Soda
Adapted from: Chemistry: Visualizing Matter (O 2000 Holt, Rinehart, & Winston)

Introduction

Baking soda (sodium hydrogen carbonate) is used to make sure that baked goods rise.
This happens because the compound breaks down and one or more gases are generated in
the process. The evidence of the generated gas is the holes or bubbles in the finished
baked good. Your job is to experimentally determine the correct chemical reaction for
the decomposition of baking soda The choices are the following reactions.

> Solid sodium hydrogen carbonate reacts to form solid sodium hydroxide and
gaseous carbon dioxide

> Solid sodium hydrogen carbonate reacts to form solid sodium oxide, gaseous
carbon dioxide, and water vapor.

> Solid sodium hydrogen carbonate reacts to form solid sodium carbonate, gaseous
carbon dioxide, and water vapor.

Materials

0 Crucible and lid 0 Ring 0 Baking soda

0 Crucible tongs o Pipestem triangle 0 Spatula

0 Balance 0 Bunsen burner

0 Ring stand 0 Plastic spoon

Procedure

All masses need to be recorded to the nearest 0. 01 g.

1) Measure the mass of the crucible. Record your data.

2) Set up the ring stand, ring, and Bunsen burner. Place the triangle on the ring.

3) Set the crucible on the triangle and heat it for 5 minutes. Use the crucible tongs to
remove the crucible fiom the triangle and set it on the wire mesh to cool for 5
minutes.

4) Measure the mass of the crucible. (Remember to use crucible tongs to handle the
crucible to prevent fingerprints that change the mass reading.) Record your data. If
your crucible mass does not vary by more tlmn 0.01 g, you may continue. If it
changed by more than 0.01 g, repeat step 3 until the mass changes by no more than
0.01 g.

5) Put enough baking soda into the crucible so that the bottom is covered. Measure the
mass of the crucible and baking soda. Record your data.

6) Place the crucible on the triangle. Position the lid so that any gas being generated can
escape.

7) Heat the crucible for 5 minutes. (The bottom should glow red-orange during the
heating.) Use the crucible tongs to remove the crucible fiom the triangle and set it on
the wire mesh to cool for 5 minutes. While it cools, use the spatula to break up any
lumps that form.

8) Use the back of your hand to test the crucible for heat being generated. If you can

comfortably hold you hand just above the crucible, it is cool enough to continue. If
not, wait another 1-2 minutes. When the crucible is cool, measure the mass and
record your data.

72

9) Heat the crucible for another 5 minutes. Use the crucible tongs to remove the
crucible fiom the triangle and set it on the wire mesh to cool for 5 minutes.

10) Repeat step 8. If the mass changes by no more than 0.01 g, you are finished. If the
mass changes by more than 0.01 g, repeat steps 8 and 9 until the mass changes by no
more than 0.01 g.

l 1) Clean up your lab area. Rinse the solid product out of the crucible and flush it down
the drain with plenty of water. Put the used crucible and lid in the “dirty crucible”
box.

 

 

 

 

 

 

 

 

 

Data Table
Before Reaction After Reaction
. Mass of crucible and solid
Mass of empty crucrble product
Mass of crucrble and baking Mass ofsolid product
soda
Mass of baking soda
Questions

Answer the following questions on a separate sheet of paper. You must show your
work to earn credit for the questions involving calculations.
1) Translate each of the given word equations into balanced formula equations.

2) Calculate the mass of baking soda prior to the reaction.
3) Calculate the mass of the solid product.

4) Use stoichiometry to convert the original mass of baking soda to mass of sodium
hydroxide.

5) Use stoichiometry to convert the original mass of baking soda to mass of sodium
oxide.

6) Use stoichiometry to convert the original mass of baking soda to mass of sodium
carbonate.

7) Compare your measured mass of product with your expected masses of sodium
hydroxide, sodium oxide, and sodium carbonate. Which chemical reaction occurred
in the crucible?

8) If the crucible was not heated long enough, would you expect the mass of the solid
product to be higher or lower than stoichiometry would predict? Explain your
answer.

73

Determining the Mass of CO2

Adapted fiom: http://tcachcrslounge.cditmccom/Stoichiomchy

Purpose

Perform a chemical reaction to analyze stoichiometry and determine percent yield.
Materials

0 250 mL beaker o 1-2 g Nal-ICO3 (sodium bicarbonate)
o 100 mL Graduated cylinder 0 100 mL CH3COOH (acetic acid)

0 Balance 0 Spoon or stirring rod

Procedure

Record all experimental data in the given data table. Record masses to the nearest 0. 01

g.

1) Take the mass of the empty beaker and graduated cylinder and record the data in the
chart below.

2) Place 1-2 g NaHCO; in the 250 mL beaker and record the actual mass used in the
data table.

3) Measure 100 mL CH3COOH in the graduated cylinder and get the mass.

4) Slowly pour all of the CH3COOH into the beaker with the NaHCOg. You must do
this slowly because if any of it fizzes over you have to start over. Be very careful!

5) Stir the reaction solution for at least 5 minutes to make sure it has reacted completely.

6) Take the mass of the beaker and the final products in the beaker. Record the data.

7) Clean up your lab area.

Data Table
Before Reaction After Reaction

 

Mass of beaker and
Mass 0f empty beaker products

 

Mass of beaker + NaHCO; Mass of products

 

 

 

Mass of NaHCO;

 

Mass of empty graduated cylinder

 

Mass of graduated cylinder + CH3COOH

 

Mass of CH3COOH

 

 

 

 

74

Questions
You must show your work on a separate sheet of paper to earn credit for the
calculations.

1)

2)

3)

4)

5)

6)

7)

3)

9)

Calculate the mass of NaHCO3 used in this reaction and record the answer in the data
table.

Calculate the mass of CH3COOH used in this reaction and record the answer in the
data table.

Calculate the apparent mass of products formed in this reaction and record the answer
in the data table.

Calculate the mass of CO2 that was formed. (Although you can’t measure the CO2
directly because it was released as a gas and became part of the air in this room, you
can calculate it by using the Law of Conservation of Mass.)

(mass of NaHCOg) + (mass of CH3COOH) = (mass of NaCH3COO + H2O) + (mass

of CO2)
+ = + mass of C02
The equation for the reaction is as follows. If it is not balanced, you need to balance
it before going to the next question. If it is balanced, please indicate that by putting a
large check mark to the left of the equation.

NaHCO3 (s) + _ CH3COOH (,q) —r _ NaCH3COO (.q) + _ H20 (1) + __ C02 (3)

Use stoichiometry to calculate the expected yield of CO2 from the initial amount of
sodium bicarbonate.

Calculate the percent yield for your reaction.

If your percent yield was not 100%, give one reason why this may have happened.
Be specific.

Using your expected amount of CO2, determine how many moles of acetic acid were
actually used in this reaction. Does this number match the amount you get when
converting the mass of acetic acid used to moles? If it does not, give a possible
reason for the discrepancy.

75

Balloon Lab
Adapted from: Chemistry (© 2000 Prentice Hall)

Materials

0 Balance 0 String (1 piece per group)

0 Graduated cylinder (1 per group) 0 Magnesium ribbon (3 pieces of varied
e 50 mL beaker (1 per group) sizes)

0 125 mL Erlenmeyer flask (1 per group) 0 50.0 mL 1.0 M HCl for each trial

0 Balloon (1 per group)

a Ruler (1 per gmup)

Procedure
Record all experimental data in the given data table. Record masses to the nearest 0. 01

g.
1)

2)
3)
4)

5)

6)

7)

3)

9)

Use tweezers to take three pieces of magnesium ribbon fi'om the supply table and put
it into the beaker. They should all be different sizes.

Use the balance and determine the mass, in grams, of one piece of magnesium. (Do
not place the magnesium directly on the balance pan.) Record the mass of the
magnesium.

Place the magnesium into the balloon.

Use the graduated cylinder to measure exactly 50.0 mL of hydrochloric acid.

Pour the hydrochloric acid into the Erlenmeyer flask.

Carefully stretch the end of the balloon over the mouth of the flask. Do not allow the
magnesium to fall into the acid while you are adding the balloon to the flask. Try to
keep as much air out of the balloon as possible.

Gently lift the balloon to drop the magnesium into the acid. Write down what you
observe.

Use the string and a ruler to measure the circumference of your balloon in
centimeters.

Repeat steps 2 through 8 for the other pieces of magnesium.

76

Data Table i -
Trial 1 Trial 2 Trial 3

 

Haas of Mg

 

Circumference of balloon

 

 

 

 

 

Questions
Answer the following questions on a separate sheet of paper. You must show your
work to earn credit for the questions involving calculations.

1) What was the purpose of this lab?
2) Write a balanced chemical equation for the reaction you observed.

3) Use stoichiometry to calculate the volume (in cm3) of hydrogen you should have
created fiom 50.0 mL ofl.0 M HCl. (100. mL of 1.0 M HCl = 0.100 moles)

4) Use stoichiometry to calculate the volume (in cm!) of hydrogen you should have
created fiom each piece of magnesium.

Trial 1 Trial 2 Trial 3

 

 

 

5) What volume (in cm3) of hydrogen did you actually produce in each trial? (HINTS:
How can you determine the radius of a sphere if you know the circumference? What
is the formula for the volume of a sphere?)

Trial 1 Trial 2 Trial 3

 

 

 

6) What was the limiting reactant in each trial — magnesium or hydrochloric acid?

Trial 1 Trial 2 Trial 3

 

 

 

7) What was your percent yield for each trial?

Trial 1 Trial 2 Trial 3

 

 

 

77

Making Chalk

Adapted from: http://colossus.chcm.umass.cdu/gcnchem/summer/chcmlll/l ll Experiment 4.htm

Introduction

In this lab, you will perform a reaction that involves the formation of a precipitate as well
as a second product tlmt remains in an aqueous solution. The precipitate in this lab is
chalk (calcium carbonate) and the reaction involved is shown below.

N32C03(,q) + C3C12(.q) —) C3CO3(S) + 2 NaClm)

At the end of the lab, you will use limiting reactant concept. In this experiment you are
given the concentration and the volume of the two solutions that you mix. Therefore you
can calculate the moles of Na2CO3 and the moles of CaCl2 that are reacted. You will use
these values to determine which reactant is the limiting reactant and to predict the amount
of CaC03 (calcium carbonate or chalk) that should be produced. Finally, you will
calculate the percent yield for the chalk that you produce. If you are carefill, you should
expect a percent yield of 80% or more.

Materials

0 2 graduated cylinders 0 Filter paper 0 Hot plate
0 0.50 M CaCl2 solution 0 Funnel o Spatula

o 1.5 M Na2CO3 solution 0 2 foil muffin cups 0 Tweezers
o 2 100 mL beakers 0 Balance

Procedure

Record all experimental data in the given data table. Record masses to the nearest 0. 01
g.

NOTE: This lab is not extremely difficult, but it requires that you make good use of your
class time. If you do not read the procedure and make sure you understand the
instructions before the lab period, you may be in danger of not finishing the activity.

1) Use a graduated cylinder to measure approximately 22 mL of 0.50 M CaCl2 solution.
Record the exact amount being used.

2) Use a graduated cylinder to measure approximately 11 mL of 1.5 M Na2C03 solution.
Record the exact amount being used.

3) Pour the liquids from both graduated cylinders in to a clean 100 mL beaker. If you do
not immediately observe the formation of a precipitate, gently swirl the beaker and
one should quickly form.

4) Gravity filter the white solid. This is done by folding a piece of filter paper into
quarters and making a cone. Place this inside your glass firnnel. Hold the firnnel over
the second beaker and pour the solution into the center of the filter paper taking care
not to let it get above the level of the filter paper. Wash the sides of the beaker with a
small amount of distilled water fiom your wash bottle and filter this liquid through
the filter paper. There will still be some while solid inside the beaker, but it is not
worth the time and effort to continue the wash and filter process to remove it.

78

5) Label one foil cup T1 for trial #1. Find the mass of the foil cup and record the value.

6) Set up a hot plate.

7) Carefully remove the filter paper from the funnel. Gently scrape the product from the
filter paper and place it on the foil cup you rmssed in the previous step. Try to get off
as much as you can without tearing or scraping off some of the filter paper. Discard
the filter paper. Place the foil cup on the hot plate and leave it for 10 minutes. (Do
not use a heat setting higher than 7.)

8) Repeat steps 1-7 using approximately 25 mL of 0.50 M CaCl2 and 1.5 M Na2CO3.
(Label this foil cup T2 for trial #2 before getting the mass.) Be sure to record the
actual amounts being used.

9) While the products are drying, begin work on the questions at the end of the lab.

10) After the product heats for 10 minutes, use the tweezers to remove the foil cup fiom
the hot plate. Place it on the counter and allow it to cool to the touch. When the foil
cup is cool, take it to the balance and get the mass. Record your data.

11) Return the foil cup to the hot plate and heat it for another 5 minutes. At the end of the
5 minutes, use the tweezers to remove the foil cup from the hot plate. Place it on the
counter and allow it to cool to the touch. When the foil cup is cool, take it to the
balance and get the mass. Record your data.

12) Repeat the previous step until you get two masses that are within 0.02g of each other.
If you follow the procedure closely, two or three beatings should be sufficient.

13) Clean your lab area.

Data

 

Trial #1 Trial #2

 

Amount of 0.50 M CaCl2 used

 

Amount of 1.5 M Na2C03 used

 

Mass of Foil Cup

 

Mass of Foil Cup and CaCOJ
after heating 1 time

Mass of Foil Cup and CaCO;
after heating 2 times

Mass of Foil Cup and CaCO3
after heating 3 times

 

 

 

 

 

 

 

79

Questions

You must show your work to earn credit for the calculations.

1) Determine the number of moles of CaC12 and Na2CO3 that were used in each trial.
Calculate the number of moles of CaCO3 expected in each trial. Show your work and
record the values in the table below.

Helpful conversion f_actors:

*when calculating moles of CaCl2, there are 0.50 moles/1 liter in the solution you

used

*when calculating moles of CaCO3, there are 1.5 moles/1 liter in the solution you

used

 

Trial #1

Trial #2

 

Moles of CaC|2
used

 

Moles of
Na2C03 used

 

Moles of CaCO;
expected

 

 

 

 

2) Was there a limiting reactant in either trial? If so which one was it?

Trial 1:

3) Determine the % yield of CaCO3 for each trial. Show your work in the space below.

% Yield for Trial 1:

 

Trial 2:

% Yield for Trial 2:

80

 

 

Airbag Activity

Purpose

To use stoichiometry to create the ideal airbag

Materials

0 Zip-top sandwich bag 0 Balance 0 Baking soda

0 Graduated cylinder 0 Weigh boat 0 50.0 mL Vinegar
Instructions

1) Balance the equation for the reaction between baking soda and vinegar.

2)

3)

4)

5)

6)

7)

__ NELHCO3 + _ C2H402 —) _ C02 + _ H20 + _ NaC2H302
Determine the volume of your sandwich bag in milliliters.

Our bag holds milliliters

 

For this lab, vinegar will be your excess reactant. Use stoichiometry to determine the
amount of baking soda that will produce enough carbon dioxide to fill the bag.
Record your calculations at the end of this page. (Use a separate sheet if you need
more space.)

Baking soda needed: grams

 

Write a procedure on the back of this sheet that you will follow when creating your
airbag. Before you continue, you must get your instructor’s approval for your
calculations and procedure.
Instructor’s initials
Follow your procedure to create an airbag. When you are ready to start the reaction,
ask your instructor to observe your reaction. A pinch test will be conducted by the
instructor at the end of your reaction to determine if the bag was over-inflated or
under-inflated.
Result of pinch test: over-inflation under-inflation

Determine whether or not all of the reactants were consumed in the reaction.

Clean up your lab area.

Calculations

81

Procedure
(Use a separate sheet of paper if you need additional space.)

Questions and Conclusions
1) Did you have any left-over reactants? How did you know? (Be specific.)

2) How is the reaction in this experiment similar to an air bag in a car? How is it
different?

3) How does figuring out the correct ratio of reactants help manufacturers of real air
bags?

4) If you were asked to do this lab again,

a. is there any extra information you would want to have? (Be specific.)

b. what would you change in your procedure? (Be specific.)

82

APPENDIX E - ASSESSMENT

83

Stoichiometry Pro-Test

Translate each of the following word equations to a formula equation. You do not

have to balance the equation. (1 pt each)

1) Aqueous sodium carbonate reacts with aqueous calcium chloride to produce solid
calcium carbonate and aqueous sodium chloride.

2) Solid magnesium reacts with aqueous hydrochloric acid to produce aqueous
magnesium chloride and hydrogen gas.

Balance each of the following equations. (1 pt each)

3) _ NaHCO3 + _ C2H402 --> _ C02 + _ H20 + _ NaC2H3O2
4) __ NaHCO3 + __ HCl —> _ NaCl + _ H2O + _ co2

5) _ NaHCO3 + _ H6C406 —) _ N32C4H4O6 + __ C02 '1' _ H20

Answer each of the following questions in complete sentences. (1 pt each)
6) In a chemical equation, what do the numbers before the chemical formulas represent?

7) If you are converting fi‘om grams to moles, what conversion information do you
need?

84

8) If you are converting from moles to liters, what conversion information do you need?

9) If you are converting from grams to liters, what conversion information do you need?

10) If you are given two reactants for an experiment, how can you determine which one is
the limiting reactant?

11) What is the difference between actual yield and theoretical yield?

85

Stoichiometry Lab Quiz

Adapted fi'om: http://departmcnts.oxv.edu/tops/Stoichiomctrv/stoichpre-post.lltm

Use the data below when answering the following questions.

 

mass of dry test tube 22.202 grams

 

mass of test tube and AglO3 23.842 grams

 

mass of copper before reaction with AgN03 5.030 grams

 

mass of copper after reaction with AgNO3 4.730 grams

 

 

 

mass of silver produced by the reaction 1.020 grams

 

1)

2)

3)

4)

5)

The mass of AgNO3 reacted is
a) 1.640 grams
b) 0.300 grams

0) 87.173 grams
d) 1.020 grams

 

The moles of AgNO; (169.91 grams/mole) reacted is
a) 0.09412 mole

b) 0.00189 mole

c) 0.5133 mole

(1) 0.009652 mole

 

The mass of copper reacted is
a) 1.600 grams
b) 0.300 grams

c) 87.170grams
d) 1.200 grams

 

The moles of copper (atomic mass 63.55 grams/mole) reacted is
a) 0.0285 moles Cu

b) 0.00472 moles Cu

0) 1.37 moles Cu

d) 0.0161 moles Cu

Based on your answers to questions 1 through 4 and the remaining data, the balanced
equation should be
a) AgNO3 + Cu —» Ag + CuNO3

b) AgNO; ‘1’ ZCU —> Ag + C02NO3

c) 2AgNO3 + 2Cu —4 2Ag + 2CuNO3
d) 2AgNO3 + Cu -> 2Ag + Cu(NO3)2

 

86

 

Stoichiometry Quiz #2

Solve the following stoichiometry problems. You may need to balance the
equations. You must show your dimensional analysis work to earn credit. Give
your answers with the correct significant digits, chemical formulas, and units.

1. How many grams of water can be prepared from 16.4 liters of hydrogen reacting with

oxygen?
H2 + 02 —-) H20

2. How many grams of iron are needed to produce 143 grams of iron (III) sulfide?
Fe + S —> F6283

3. 36 liters of chlorine gas react with hydrobromic acid at STP to yield how many liters
of bromine gas?
HBrtg) + C12 (g) —) HCl (3) + BT2 (g)

87

Stoichiometry Quiz #3

Solve the following stoichiometry problems. You may need to balance the
equations. You must show your dimensional analysis work to earn credit. Give
your answers with the correct significant digits, chemical formulas, and units.

1. Given 111.7 g Fe & 160.35 g S, how many grams of product can be formed?
Fe ‘1' S -) F6283

2. Given 3.5 g copper & 6.0 grams silver nitrate, how many grams of silver can be
formed?
Cu + AgNO3 -—) Cu(NO3)2 + Ag

3. 5.00 grams of copper are mixed with an excess of silver nitrate. In the end, 15.2
grams of silver are recovered. What is the percent yield?
Cu + AgNO3 —> CuCNO3)2 + Ag

88

Stoichiometry Test
© Yes, you may write on this one! CD

Translate each of the following word equations to a formula equation. You do not

have to balance the equation. (1 pt each)

1) Aqueous sodium carbonate reacts with aqueous calcium chloride to produce solid
calcium carbonate and aqueous sodium chloride.

2) Solid magnesium reacts with aqueous hydrochloric acid to produce aqueous
magnesium chloride and hydrogen gas.

Balance each of the following equations. (1 pt each)

3) _ NaHCO3 + _ C2H402 -) __ C02 + __ H20 + _ NaC2H302
4) __ NaHCO3 + _ HCl —> _ NaCl + _ H2O + _ co;

5) _ NaHCO3 + _ H6C406 —> _ N32C4H406 + _ C02 + _ H20

Answer each of the following questions in complete sentences. (1 pt each)
6) In a chemical equation, what do the numbers before the chemical formulas represent?

7) If you are converting fiom grams to moles, what conversion information do you
need?

89

8) If you are converting fi'om moles to liters, what conversion information do you need?

9) If you are converting fi'om grams to liters, what conversion information do you need?

10) If you are given two reactants for an experiment, how can you determine which one is
the limiting reactant?

11) What is the difference between actual yield and theoretical yield?

90

Write the letter of the appropriate answer on the line next to the definition. (1 pt

each)

12)

13)

14)

15)

16)

17)

18)

19)

20)

21)

Starting materials in a chemical reaction

Total amount of product produced
in a chemical reaction

Determining the grams of products
fiom a given number of grams
of reactants

Substance that determines how
much product may be formed

Determining the liters of products fiom
a given number of grams of reactants

Maximum amount of product to
be formed in a chemical reaction

Determining the grams of products
fiom a given number of liters of
reactants

Avogadro’s number of particles

Determining the liters of products fiom
a given number of liters of reactants

Comparison of expected and actual
amounts of product

91

F1

.3 .0

H
e

Actual yield
Limiting reactant
Mass—)mass
conversion
Mass—wolume
conversion

Mole

Percent yield
Reactants
Theoretical yield
Volume—)mass
conversion
Volume—wolume

conversion

Answer the following question. Remember to do each of the following:
0 balance the chemical equation (1 pt)
0 show all dimensional analysis work (including units) (2 pts)
0 give an answer with the appropriate units and number of significant digits
(2 ptS)
(Remember to keep all digits when calculating molar masses.)

22) How many moles of nitrogen are needed to produce 3.9 moles of ammonia?
N2 + H2 —) NH3

Answer three of the following questions. Remember to do each of the following:
0 balance the chemical equations (1 pt)
0 show all dimensional analysis work (including units) (2 pts)
0 give an answer with the appropriate units and number of significant digits
(2 pts)
(Remember to keep all digits when calculating molar masses.)

23) How many liters of oxygen are needed to produce 78.93 g of water?
H2 + 02 —) H20

24) How many grams of lithium hydroxide can be produced from 4.0 grams of lithium?
Li + H2O —> LiOH + H2

25) How many grams of silver oxide are needed to produce 5400 liters of oxygen?
Ag2O —) Ag + 02

92

26) 92.8 liters of butane can be used to produce how any liters of carbon dioxide?
C4H1() + 02 —) C02 + H20

Answer the following question. Remember to do each of the following:
0 show all dimensional analysis work (including units) (4 pts)
0 give answers with the appropriate units and number of significant digits
(4 pm)
0 tell which reactant was the limiting reactant (1 pt)
(Remember to keep all digits when calculating molar masses.)

27) A chemistry student was working on an experiment to produce copper fiom copper
(II) sulfate and iron filings. The materials available for the experiment were 7.82
grams of iron and 45.9 grams of copper (II) sulfate. How much copper could be
produced?

Fe + CuSO4 —-) Cu + Fe 304

Answer the following question. Show your work. Give your answer with the
correct number of significant digits and appropriate units. (3 pts)

28) If the student in the previous question produced 6.31 grams of copper at the end of
the experiment, what was the percent yield?

93

APPENDIX F - STUDENT DATA

94

 

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*Possible scores for each assi ent are in bold beneath the title

Table 3 — Student Scores for Activities (hours 1, 2, & 4)

see

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2.8.3

95

 

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Table 4 -— Student Scores for Activities (hours 5 & 6)

 

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*Possible scores for each assignment are in bold beneath the title

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5-8

 

 

10
10
10
10
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96

Table 5 - Student Scores for Quizzes and Posttest (hours 1, 2, & 4)
*Possible scores for each assignment are in bold beneath the title

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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1-4 M 10 3 ll 12 31
1-5 F 10 1 9 5 33
1-6 F 10 3 8 7 38
l-7 F 11 4 9 4 37
1-8 F 10 l 11 11 37
1-9 F 10 2 l l 30
2-1 M 10 4 6 5 31
2-2 M 10 4 12 10.5 39
2-3 F 10 2 12 15 42
2-4 M 10 4 12 13.5 41
2-5 M 10 4 11 8.5 33
4-1 F 11 3 6 0 31
4-2 F 10 4 12 15 45
4-3 F 10 2 7 6 36
4-4 F 10 3 1.0 6 37
4-5 F 10 3 12 17 37
4-6 M 10 0 9 5.5 29
4-7 F 11 4 0 8.5 20

 

 

 

 

 

97

 

Table 6 — Student Scores for Quizzes and Posttest (hours 5 & 6)
*Possible scores for each assignment are in bold beneath the title

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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