Stoichiometry is Cooking
Stoichiometry is Cooking
5E Lesson Plan, Author: Sara Rosario, Yakima WATERS Project, CWU, Fall 2010
Stoichiometry is the quantitative relationship between the reactants and productions in a
chemical reaction. Stoichiometry involves indentifying proportional relationship between
reactants and products, to alter stoichiometric coefficients to balance chemical equation and to
use stoichiometric coefficients to obtain quantitative information. In this lesson students will
learn Stoichiometry, by first examining the proportions of ingredients in cookie recipes then by
balancing chemical equations, calculating limiting reagents, and theoretical yields. This lesson is
appropriate for 11th and 12th graders and should take an hour to an hour and 20 minutes to
complete.
Standards
Science standards for Matter: properties and change
9-11 PS2E - Molecular compounds are composed of two or more elements bonded together in a
fixed proportion by sharing electrons between atoms, forming covalent bonds. Such compounds
consist of well-defined molecules. Formulas of covalent compounds represent the types and
number of atoms of each element in each molecule
9-11 PS2G - Chemical reactions change the arrangement of atoms in the molecules of
substances. Chemical reactions release or acquire energy from their surroundings and result in
the formation of new substances.
Math standards
A1.8.A - Analyze a problem situation and represent it mathematically.
A1.8.C - Evaluate a solution for reasonableness, verify its accuracy, and interpret it in the
context of the original problem.
A1.3B. - Represent a function with a symbolic expression, as a graph, in a table, and using
words, and make connections among these representations.
A1.8.G - Synthesize information to draw conclusions and evaluate the arguments and
conclusions of others.
Outcomes
Upon completion students should be able to identify proportional relationships between
reactants and products (Ex: if there are 2 moles of oxygen in the reactant then student should
be able to determine that there should be 2 moles of oxygen in the products) and see how
changes in the stoichiometric ratios affect the outcome of a reaction in this case their cookies.
At the end of this lesson students should also be able to balance chemical equations, obtain
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quantitative information such as moles and mass from chemical equations, and find limiting
reagents and theoretical yields.
Materials and Equipment
For 36 students you will need 10 lbs flour, 5lbs granulated sugar, 5 lbs brown sugar, 5 lbs semisweet chocolate chips, 2 dozen eggs and a large package of rolled oats. For the rest of the dry
ingredients you will need a pound of each, for the wet ingredients you will need at least 12
ounces of each.
Food stuff: Flour, sugar, butter, eggs, rolled oats, chocolate chips, coco powder, shredded
coconut, walnuts, almonds, dried cranberries, peanut butter, honey, hot water, vanilla extract,
baking soda.
Utensils: large mixing bowls, small microwave safe bowls, wooden spoons, measuring cup and
measuring spoons, aluminum foil, hot plates, small sauce pans or small pots and electronic
balances. You will need access to an oven or to two or three tosterovens and microwave ovens.
Cookie recipes are in resources section. Please note that all the recipes converted to grams
measurement to make the math easier.
Prior Knowledge
Students must also know the law of conservation of mass. Students should be able to perform
simple arithmetic and be able to multiply and divide fractions prior to this lesion. Students
should have had significant exposure to chemical equations. It may also be helpful for students
to be able to perform determinants and combine algebraic equations.
Safety
In this lesson student will be asked to make cookies, be sure to ask students about food
allergies. And alter recipes as needed. Also be sure to supervise students with ovens.
Engage (10 min)
In the resources section you will find the Grilled Cheese Sandwich Stoichiometry Formative
assessment. This is fun assessment that can be used as either a formative assessment or an
introductory activity to get students started thinking about stoichiometry.
Explore (15 min)
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Pairs of students will be giving a recipe and ingredients and utensils (you may find it help full to
have bags of premeasured ingredients with the ingredient name and quantity written on the
bag, wooden spoons and measuring utensils with the mixing bowl). You can either tell students
that they must alter their recipe to make a ½ dozen cookies or you may decrease the quantity
of one ingredient and have the students adjust the recipes to match. I personally prefer the
latter as it more closely resembles common stoichiometry problems. You can also have all the
students prepare variations of the same recipe. For example group I no variations, groups II use
5 g (1 teaspoon) baking powder instead of two, group III use 10 g (2 teaspoons) baking soda
instead of baking powder, group IV use one egg, group V use no eggs and group VI use 180 ml
(3/4 cup) butter instead of 60 ml (1/4 cup). Have the students work out their recipe
stoichiometry on a separate sheet of paper. This is a good place to introduce students to
limiting reagents and theoretical yields by having students determine the limiting reagent and
calculate theoretical yield. Be sure they know they must use all of the ingredients mentioned in
the recipe. Once they have completed their alteration check their work and have them make
their cookies. When their cookies are ready to bake you may needed to transport the cookies to
the oven or assist student with the toaster ovens. When the cookies are done baking and
cooling students will be asked asses the success of their recipe see rubric below. While cookies
are baking do the explain portion of this lesson.
Explain (10 min)
Have students explain how they altered their cookie recipes, what was their line or reasoning,
how did they determine the amounts of each ingredient to be used and how they think the
changes will affect the final product. If students devised different methods to alter the recipes
have them share their method with the class. Ask students to compare the amounts of each
ingredient in their recipes before and after baking, one way to do this is to have students
calculate the mass of each ingredient in one cookie. Ask student to account for all ingredients in
the cookies; were there any gains or losses in the amounts of each ingredient? It is especially
important that students understand the relationship between the ingredients in the finished
cookies. The proportion of each ingredient should be the same in the recipe and finished
cookie. Please refer to the proportional recipes in the resources section as these recipes give
the ratio of mass of each ingredient in one cookie.
Extend/Elaborate (20 min)
Next explain to the student that what they did was stoichiometry (it may be helpful to write out
the cookie recipes like a chemical equation). Define Stoichiometry and the rules of
stoichiometry. Explain what stoichiometric coefficients are and be sure to relate the coefficients
to the amount (moles or mass) of ingredients in recipes or chemical reactions. It is extremely
important that students understand that stoichiometric coefficients represent numbers of
molecules not quantities such as grams or liters. For example;
3H2 + N2 → 2NH3
The reaction above can be read as 3 molecules of H2 plus 1 molecule N2 yields 2 molecules of
NH3. Or you can read the reaction as 3 dozen H2 plus 1 dozen N2 yields 2 dozen NH3.
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Stiochoimetric coefficients represent proportion of each atom involved in the chemical
reaction. Have the students work with you to balance two or three simple chemical equations.
As a class work thru some limiting reagent and theoretical yield problems, when this is done
give the students the stoichiometry is cooking worksheets attached and have them do it. On
this worksheet students must they must balance chemical equations; find theoretical yields and
limiting reagents of chemical reactions and recipes.
Evaluate (10 min)
Students will be asked to evaluate their finished cookies using the student cookie rubric
provided below. Ask students to think about how alterations in amount of ingredients may have
affected the cookies and how they might improve the recipes for the future. Students will also
be asked to turn in their worksheets, this worksheet can be graded using the rubric. If you have
only 50 minute to complete this lesson student may work their worksheet at home and turn it
in later.
Property
Description
Moisture
Texture
Consistency
Dimensions
(height and
diameter)
Taste
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Performance Rubric
Element
Excellent
(5 pts)
Good
(4 pts)
Conceptual
Understanding
(1, 20%)
Student should
get questions 5,
9 and 10
correct. On
question 4
students should
be able to
provide a
logically
explanation of
the steps they
took to solve
the problem.
Skill 1,
Balancing
Chemical
Equations (1,
20%)
Student is able
to apply
stoichiometry to
balance
chemical. This
means the
student answers
question 2, 4
and 5 correctly
on the student
work sheet. On
question 4 the
student should
be able to
provide a logical
explanation as
to why they
chose the
coefficients
values they
chose.
The student is
able to correctly
answer question
3 correctly. And
is able to
provide a logical
explanation of
the steps they
took to solve
the problem.
Student may
answer one
question (Qs
5, 9 and 10)
incorrectly. On
question 4
students
should be able
to provide a
muddy
explanation of
the steps they
took to solve
the problem.
The student
may answers
one of
question 2, 4
and 5
incorrectly. On
question 4 the
student should
be able to
provide a
logical
explanation as
to why they
chose the
coefficients
values they
chose.
Skill 2,
Calculating
Mass and
moles from
stoichiometric
coefficients (2,
20%)
In
Development
(3 pts)
Student may
answer two
questions (Qs
5, 9 and 10)
incorrectly. On
question 4
student should
be able to
provide a
muddy
explanation of
the steps they
took to solve
the problem..
The student
may answers
two of question
2, 4 and 5
incorrectly. On
question 4 the
student should
be able to
provide a
muddy
explanation as
the coefficients
they chose.
The student is
not able to
correctly
answer
question 3
correctly. And
is able to
provide a
muddy
explanation of
the steps they
took to solve
5
Needs Rethinking
(2 pts)
Not Scorable
(1 pt)
Student may
answer questions
5,9 and 10
incorrectly. On
question 4
student may not
be able to provide
a sensible
explanation of the
steps they took to
solve the
problem.
Student may
answer all three
questions
incorrectly. On
question 4 student
did not provide any
explanation of the
steps they took to
solve the problem.
Student may
answer all three
questions
incorrectly. On
question 4.
Student may not
be able to provide
a sensible
explanation of the
coefficient they
chose.
Student may
answer all three
questions
incorrectly. On
question 4. Student
did not provide any
explanation of the
steps they took to
solve the problem.
The student is not
able to correctly
answer question 3
correctly. And is
unable to provide
any explanation of
the steps they took
to solve the
problem.
Skill 3,
Calculating
limiting
reagent and
theoretical
Yield (3, 40%)
The student
should be able
to answer
question
1,4,5,6,7 and 8
correctly .
The student
should be able
to answer
question
1,4,6,7 and 8
correctly.
the problem.
The student
should be able
to answer
question 1,4,7
and 8 correctly.
The student
should be able to
answer question 1
and 4 correctly.
The student cannot
answer question
1,4,5,6,7 and 8
correctly.
Teacher Background Info
Stoichiometry is the quantitative relationship between the reactant and products of a chemical
reaction. Stoichiometry is used to balance chemical equations and there are a few assumptions
that must be made about the chemical reactions to do this. Assumption one: all reagents are
consumed in the reaction. Assumption two: no side reactions occur and assumption three: no
atoms are lost in the reaction.
Resources
Recipes
ANZAC Biscuits:
128 g Flour
85 g Rolled oats
220 g Brown sugar
71 g shredded coconut
46 g Almonds
46 g Cranberries
57 g Butter
43 g Honey
30 g Water
Mix together flour, brown sugar, rolled oats, shredded coconut, almonds and cranberries in a
large mixing bowl until combined and set aside. In a pot place butter, honey and water, place
on hot plate and heat until everything is melted. After melting stir and pour the melted mixture
into the mixture of dry ingredients. Mix until all ingredients are combined. Roll dough into 15g
(about one inch in diameter) balls, place the dough balls onto a baking sheet at least 1 ½ inches
apart. Bake for 10 minutes at 350⁰C. Makes 4 Dozen Cookies.
Oatmeal Chocolate Cookies:
256 g Flour
6
43 g Rolled Oats
227 g Butter 2 Eggs
46 g Walnuts
150 g Sugar
165 g Brown Sugar
228 g Chocolate Chips
12 g Baking Soda
15 g Vanilla
Mix butter, sugar, brown sugar in a large mixing bowl, until the mixture appears fluffy and
creamy. Add eggs and vanilla and stir until combined. Now add now add flour, oats and baking
powder, stir to combine. Add walnuts and chocolate chip and stir to combine. Roll dough into
19.8 g (about one inch in diameter) balls place the dough balls onto a baking sheet about 1 ½
inches apart. Bake for 12 minutes at 350⁰C. Makes 5 dozen cookies.
Chocolate Chocolate Chip Cookies:
288 g Flour
64 g Coco Powder
227 g Butter
46 g Eggs
46 g Walnuts
201 g Sugar
220 g Brown Sugar
228 g Chocolate Chips
12 g Baking Soda
15 g Vanilla
Mix butter, sugar, brown sugar in a large mixing bowl, until the mixture appears fluffy and
creamy. Add eggs and vanilla and stir until combined. Now add now add flour, coco powder and
baking powder, stir to combine. Add walnuts and chocolate chip and stir to combine. Roll
dough into 22.45 g (about one inch in diameter) balls, place the dough balls onto a baking sheet
about 1 ½ inches apart. Bake for 12 minutes at 350⁰C. Makes 5 dozen cookies.
Drop Sugar Cookies with Walnuts:
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256 g Flour
113 g Butter
26 g Egg
46 g Walnuts
201 g Sugar
12 g Baking Soda
15g Vanilla
Mix butter and sugar in a large mixing bowl, until the mixture appears fluffy and creamy. Add
eggs and vanilla and stir until combined. Add walnuts and stir to combine. Roll dough into 13.88
g (about one inch in diameter) balls, place the dough balls onto a baking sheet about 1 ½ inches
apart. Bake for 12 minutes at 350⁰C. Makes 4 dozen cookies.
The ANZAC Biscuits recipe is appropriate for student whom have below average math skills. The
Chocolate Chocolate Chip and Drop Sugar Cookie with Walnut recipes are more appropriate for
student with average math skills. The Oatmeal Chocolate Chip cookie recipes is appropriate for
student with above average math skills.
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Name:
Date:
Period:
Stoichiometry is Cooking Worksheet
1) You want to 6 make grilled cheese sandwiches (use the equation below, Bd = bread and Ch =
Cheese) and you have 13 slices of bread and 5 slices of cheese. How may grilled cheese
sandwich can you make? And what is the limiting reagent?
2Bd + Ch→Bd2Ch
2) Balance the equation below.
O2 + H2→H2O
Zn + S→2 ZnS
NH4 + 2 OCN→CON2H4
3) Balance the equation below and determine the number of moles and the mass of each
reactant required to make one mole of product. After each step write a sentence or two
explaining why you did what you did.
CO + H2→ CH3OH
C3H7SH + I2→C6H14S2 + HI
4) You are having some friends over for dinner you want to make 8 cheese burgers, you have 8
hamburger patties, 12 bums, 7 slices of cheese, 18 slices of tomato, 16 pieces of lettuce and 9
slices of onion. Use the equation below (where buns = B, hamburger patty = H, cheese = Ch,
tomatoes = T lettuce = L and onion = O) to determine how many cheese burgers you can make
(what’s your theoretical yield?)and what the limiting reagent is? Hint you may need to balance
the equation first.
B+ H+ Ch+ 2T+ 2L+O → BHChT2L2O
5) Balance the chemical equations below. Find the limiting reagent and the theoretical yield if
there is one gram of each reagent. After each step write a sentence or two explaining why you
did what you did.
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CH4 + 2O2 → CO2 + H2O
6) Balance the chemical equations below. Find the limiting reagent and the
theoretical yield if there is one gram of each reagent.
LiOH + CO2 → LiCO3 + H2O
2KClO3 → KCl + 3O2
C3H8 + O2 → 3CO2 + 4H2O
Zn + 2AgNO2 → Ag + Zn(NO3)2
7) You have 12 leftover waffles from breakfast yesterday morning so you decide to make Waffle
Sammies. You have two sliced bananas, ½ cup peanut butter and ½ cup strawberry jelly. Use
the equation below (where waffles = W, bananas = B, peanut butter = P and strawberry jelly =
S) to determine how many waffle sammies you can make and what is the limiting reagent?
8W + 2B+ ¼ P + ¼ S → 4W2B1/2P1/16S1/16
8) Smore Stoichiometry. You have one chocolate (Co) bar (which yields enough chocolate for
four smores), a box of gram crackers(Gc) and 13 large marshmallows (M). Using the equation
below determine how many smores you can make and what the limiting reagent is?
2Gc + Co + M → Gc2CoM
9) What must be the same before and after a chemical reaction?
10) What do stoichiometric coefficients tell us about chemical reactions?
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Name:
Date:
Period:
Grilled Cheese Stoichiometry
1) You want to 6 make grilled cheese sandwiches (use the equation below, Bd = bread and Ch =
Cheese) and you have 13 slices of bread and 5 slices of cheese.
2Bd + Ch→Bd2Ch
How may grilled cheese sandwich can you make? And what is the limiting reagent?
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Proportional Recipes:
Remember these recipes are ratios of ingredient masses in one cookie, so if you multiple this
ratio by the number of cookies the recipe should make you will get the mass of each ingredient
required to make a full recipe.
ANZAC Biscuits:
2.66 Flour
1.77 Rolled oats
4.58 Brown sugar
1.48 shredded coconut
0.95 Almonds
0.96 Cranberries
1.19 Butter
0.89 Honey
0.63 Water
Mix together flour, brown sugar, rolled oats, shredded coconut, almonds and cranberries in a
large mixing bowl until combined and set aside. In a pot place butter, honey and water, place
on hot plate and heat until everything is melted. After melting stir and pour the melted mixture
into the mixture of dry ingredients. Mix until all ingredients are combined. Roll dough into 15g
(about one inch in diameter) balls, place the dough balls onto a baking sheet at least 1 ½ inches
apart. Bake for 10 minutes at 350⁰C. Makes one Cookies.
Oatmeal Chocolate Cookies:
4.26 Flour
0.72 Rolled Oats
3.78 Butter 2 Eggs
0.76 Walnuts
2.5 Sugar
2.75 Brown Sugar
3.8 Chocolate Chips
0.25 Baking Soda
0.2 Vanilla
Mix butter, sugar, brown sugar in a large mixing bowl, until the mixture appears fluffy and
creamy. Add eggs and vanilla and stir until combined. Now add now add flour, oats and baking
powder, stir to combine. Add walnuts and chocolate chip and stir to combine. Roll dough into
19.8 g (about one inch in diameter) balls place the dough balls onto a baking sheet about 1 ½
inches apart. Bake for 12 minutes at 350⁰C. Makes 5 dozen cookies.
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Chocolate Chocolate Chip Cookies:
4.8 Flour
1.06 Coco Powder
3.78 Butter
0.76 Eggs
0.76 Walnuts
3.35 Sugar
3.66 Brown Sugar
3.8 Chocolate Chips
0.2 Baking Soda
0.25 Vanilla
Mix butter, sugar, brown sugar in a large mixing bowl, until the mixture appears fluffy and
creamy. Add eggs and vanilla and stir until combined. Now add now add flour, coco powder and
baking powder, stir to combine. Add walnuts and chocolate chip and stir to combine. Roll
dough into 22.45 g (about one inch in diameter) balls, place the dough balls onto a baking sheet
about 1 ½ inches apart. Bake for 12 minutes at 350⁰C. Makes 5 dozen cookies.
Drop Sugar Cookies with Walnuts:
5.33 Flour
2.35 Butter
0.48 Egg
0.96 Walnuts
4.19 Sugar
0.25 Baking Soda
0.31 Vanilla
Mix butter and sugar in a large mixing bowl, until the mixture appears fluffy and creamy. Add
eggs and vanilla and stir until combined. Add walnuts and stir to combine. Roll dough into 13.88
g (about one inch in diameter) balls, place the dough balls onto a baking sheet about 1 ½ inches
apart. Bake for 12 minutes at 350⁰C. Makes 4 dozen cookies.
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