Chemical Reactions – Grade 10 Academic
Lesson Sequence
Lesson Plan Title
Names
First Lesson
Conservation of Mass
Anthony De Giorgio
Antonette Montanaro
Second Lesson
Writing Balanced Chemical
Kalvin Lau
Equations
Holly Wykes
Rationale: The above lessons are dates 4 and 5 in a 20-day Chemistry Unit. They are the first and second
lessons in the Chemical Reactions chapters, following Ions, Molecules and Compounds and preceding
Acids and Bases. They support the Big Ideas by explaining the predictable ways in which chemicals react
with each other. They also introduce the possible negative impact that chemical reactions may pose to
the environment. Each lesson aims to answer its own Learning Goals by providing a thorough
foundation, analysis and application of the Conservation of Mass and Balancing Chemical Equations.
Written practice, demonstrations, model construction and higher order thinking application questions
contribute to the students’ learning process.
Unit Plan
Grade 10 Academic: Chemistry
1. Matter and the
Periodic Table
2. Ions, Molecules
and Compounds
3. Ions, Molecules
and Compounds
(Cont’d)
Quick Lab
4. Chemical
Reactions:
- Chemical
Reactions
- Conservation of
Mass
5. Chemical
Reactions:
- Writing Balanced
Chemical
Equations
6. Chemical
Reactions:
- Strategies for
Balancing
Chemical
Equations
11. Using
Neutralization
reactions to Solve
Environmental
Challenges
- Group Activity
7. Quiz: Balancing
Chemical
Reactions
Introduction to Acids
and Bases
8. Properties of Acids
and Bases
- Identifying Acids
- Identifying Bases
9. Lab and Report:
Acids and Bases
10. Neutralization
Reactions
- Neutralization
12. Group
Presentations
13. Types of Chemical
Reactions:
- Synthesis
Reactions
14. Types of Chemical
Reactions:
- Decomposition
Reactions
15. Combustion
Reactions
16. Single
Displacement
Reactions
17. Double
Displacement
Reactions
18. Environmental
Application
19. Unit Review
20. Unit Test
Quiz: Acids and
Bases
Lab and Report:
Combustion
Review Sheet
Handed Out
Theme 1: Matter and the Periodic Table, Ions, Elements & Compounds – Pink
Theme 2: Chemical Reactions – Blue
Theme 3: Acids and Bases – Purple
Theme 4: Types of Chemical Reactions – Green
Theme 5: Review and Unit Test - Yellow
2
“Be the change you want to see in the world!” -Mahatma Gandhi
NAMES: Anthony De Giorgio and Antonette Montanaro
UNIT: Chemical Reactions
TITLE OF LESSON: Types of Reactions and Law of Conservation of Mass
BIG IDEAS:
MATERIALS:
- Chemicals react with each other in
- Eggs
predictable ways.
- Skillet
- Chemical reactions may have a negative
- Ice cubes
impact on the environment, but they can
- Strainer
also be used to address environmental
- 2 beakers
challenges.
- Pop can (one crushed, one not)
- 2 teaspoons
MINISTRY EXPECTATIONS:
- Salt
- C2.1 Use appropriate terminology related
- Water
to chemical reactions, including, but not
- 6 Glow-sticks
limited to: compounds, product & reactant.
- 6 Icepacks
- C3.1 Describe the relationship between
- Vinegar
chemical formulae, composition and the
- Baking soda
names of binary compounds (e.g., Carbon
- Scale
dioxide, CO2, has two oxygen atoms and
- Play dough (red, white, blue and yellow)
one carbon atom).
- Appropriate worksheets (B1.0; B2.1; B1.4)
- C3.2 Explain, using the law of conservation
of mass and atomic theory, the rationale for
balancing chemical equations.
- C3.3 Describe the types of evidence that
indicate chemical change (e.g., changes in
colour, the production of gas, the formation
of precipitate, the production of absorption
of heat, the production of light).
STUDENT LEARNING GOALS:
APPENDICES:
1. Introduction to terminology and the
A1.0 Chemical vs. Physical Change Egg Demonstration:
components of chemical reactions.
Teachers Notes
2. What makes a chemical reaction? How to B1.0 Physical or Chemical Change Carousel Activity:
distinguish what is and what is not a
Worksheet
chemical reaction.
B1.1 Physical or Chemical Change Carousel Activity:
3. Representing chemical reactions through Answer Key
the formation of chemical equations.
B2.0 Chemical and Physical Changes, Chemical Equations
4. Introduction to law of conservation of mass and Conservation of Mass Chalkboard Notes
and balancing chemical equations.
B2.1 Chemical and Physical Changes, Chemical Equations
and Conservation of Mass Handout
B3.0 Law of Conservation of Mass Worksheet
B3.1 Law of Conservation of Mass Worksheet: Answer Key
C1.0 Chemical Reactions that Affect our Environment
PRIOR KNOWLEDGE:
Homework Sheet
Definitions and examples of: The Periodic Table,
Components of an Atom, the Physical Properties of
Matter, the Chemical Properties of Matter and
Molecular and Ionic Compounds.
3
T/L STRATEGIES
RATIONALE
A
1) Chemical Vs. Physical Change Allow students observe a
Egg Demonstration:
physical and chemical
MINDS ON
A
short
demonstration
of
the
physical
change, and to get them
(10-15
change that occurs when you break thinking about how a
minutes)
and egg shell and the chemical change physical change may be
that occurs when you fry an egg.
different from a chemical
Appendix A1.0
change.
B
1) Physical or Chemical Change Allow students to discover
Carousel:
what constitutes a
ACTION
chemical change. Allows
(15-20 Have six different stations: Three
demonstrating physical changes,
students to start thinking
minutes)
three demonstrating chemical
about how/why chemical
changes.
changes are different from
Appendix B1.0; Appendix B1.1
physical changes.
2) Chemical & Physical Changes, Provides students with a
Chemical Equations and
hard copy of the main
(15-20
Conservation
of
Mass
Notes:
ideas. Allows students to
minutes
Notes on characteristics of physical consolidation information.
changes and chemical reactions,
reactants & products and chemical
equations. Use concrete materials
(model atoms) to demonstrate
chemical equations.
Appendix B2.0; B2.1
3) Chemical Equations and
Gives students a way to
(15-20
Conservation of Mass Group “see” chemical equations
minutes)
Activity:
with solid objects and to
In groups of 4, students are given
reinforce the Law of
simple equations to determine the
Conservation of Mass:
number of atoms on the reactant and “In a chemical reaction,
product side of the equation. They are the mass of the products
given scales and play-dough to make always equals the mass of
sure that the reactants are equal to the reactants”.
the products. Following the group
activity, there will be a small debrief
led by the teacher to discuss findings.
Appendix B3.0; B3.1
C
1) Combustion Notes:
Extend thinking to analysis
CONSOLID- Together, the class will read the
and application.
ATION & information on the sheet and briefly
CONNEC- discuss the questions.
TION
(5-10
Appendix C1.0
minutes)
ASSESSMENT
Predict/ Observe/ Explain
In groups Think/ Pair/ Share
Questioning during notemaking.
Think/ Pair/ Share, questioning
while taking up the worksheet.
Read hand-out and answer
questions for homework.
NEXT STEPS Writing Balanced Chemical Equations
4
Appendix A1.0 - Minds On
Chemical vs. Physical Change Egg Demonstration – Teachers Notes

-
-

Purpose: demonstrate the difference between a physical and chemical change.
Display of egg in front of class.
Crack the egg into a clear bowl
Questions to ask:
“I cracked this egg into this bowl, what kind of change do you think I have produced? Physical or Chemical?”
Answer: Physical, because I have not changed the state of the egg? I have not changed its molecular structure. I
have simply displaced its parts.
Predict: “What do you think will happen when I drop this cracked egg into the heated skillet? Will it produce a
chemical or physical change?”
Observe: Teacher cracks the egg into the skillet, and it cooks.
Explain: It is a Chemical change, because the molecular structure of the egg is changing; and will never be able
to return back to its original state.
5
Appendix B1.0 - Action
Physical or Chemical Change Activity Worksheet
Instructions:
* Your teacher will put you into number groups. Station number is the same as your group number.
* Follow the instructions for that station and document your observations and conclusions in the space provided.
* When your teacher says, you will move in a clockwise direction to your next station.
Physical or Chemical Changes?
Station #1
Station #2
Materials: 2 soda cans are displayed. One of
them is crushed, the other is not.
Materials: 6 non-cracked glow-sticks
Instructions at station:
2. Look at both the crushed soda can and noncrushed soda can.
3. Write down observations about the two
cans.
1. Is this a physical or chemical change?
Instructions at station:
2. Observe a non cracked glow-stick.
1. Write down your observations.
2. Now carefully crack the glow-stick and
observe what happens.
3. Write down observations.
4. Is this a physical or chemical change?
6
Physical or Chemical Changes?
Station #3
Station #4
Materials: Ice cube, small strainer and beaker.
The small strainer is placed on top of the beaker
and the ice in the strainer.
Material: Icepack
Instructions at station:
1. Look at the ice at this station and the pool of
water it is creating.
2. Write down your observations.
3. Is this a physical or chemical change?
Instructions at station:
1. Observe and feel a non-cracked ice-pack.
2. Write down your observations
3. Now, carefully crack the icepack.
4. Observe and feel the icepack once more after
it has been cracked.
5. Write down your observations
6. Is this a physical or chemical change?
7
Physical or Chemical Changes?
Station #5
Station #6
Materials: water, salt, beaker and teaspoon
Materials: Vinegar, baking soda, beaker,
teaspoon and sink
Instructions at station:
1. Fill your beaker half way with water
2. Write down observations
3. Add a teaspoon of salt into the beaker.
4. Write down observations.
5. Is this a physical or chemical change?
Instructions at station:
1. Fill your beaker a quarter of the way full.
2. Write down observations.
3. Place beaker in the sink, then add a teaspoon
of baking soda to the vinegar.
4. Write down observations.
5. Is this a physical or chemical change?
8
Appendix B1.1 - Action
Physical or Chemical Change Activity –Teacher’s Copy
Physical Change Stations
Chemical Change Stations
Station #1
Station #2
Materials: 2 soda cans are displayed. One of
them is crushed and the other is not.
Materials: 6 non-cracked glow-sticks
Instructions at station:
* Look at both the crushed soda can and noncrushed soda can.
3. Write down observations about the two
cans.
4. Is this a physical or chemical change?
Instructions at station:
2. Observe a non-cracked glow-stick.
3. Write down your observations.
4. Now carefully crack the glow-stick and
observe what happens.
5. Write down observations.
6. Is this a physical or chemical change?
9
Physical Change Stations
Chemical Change Stations
Station #3
Station #4
Materials: Ice cube, small strainer and beaker.
The small strainer is placed on top of the beaker
and the ice in the strainer.
Material: Icepack
Instructions at station:
5. Look at the ice at this station and the pool of
water it is creating.
6. Write down your observations.
7. Is this a physical or chemical change?
Instructions at station:
4. Observe and feel a non-cracked ice pack.
5. Write down your observations
6. Now, carefully crack the icepack.
7. Observe and feel the icepack once more after
it has been cracked.
8. Write down your observations
9. Is this a physical or chemical change?
10
Physical Change Stations
Chemical Change Stations
Station #5
Station #6
Materials: water, salt, beaker and teaspoon
Materials: Vinegar, baking soda, beaker,
teaspoon and sink
Instructions at station:
7. Fill your beaker half way with water
8. Write down observations
9. Add a teaspoon of salt into the beaker.
10.
Write down observations.
11.
Is this a physical or chemical change?
Instructions at station:
6. Fill your beaker a quarter of the way full.
7. Write down observations.
8. Place beaker in the sink, and then add a
teaspoon of baking soda to the vinegar.
9. Write down observations.
10.
Is this a physical or chemical change?
11
Appendix B2.0 - Action
Chalkboard Notes:
Physical and Chemical Reactions
1) The Egg experiment/demonstration showed us that matter could both physically and chemically undergo change.
- The cracking of the shell is a physical change because no new matter is being formed; only the shape is being changed.
- The cooking of the egg is a chemical change because bonds are being broken down and new matter is being formed.
Also heat is being absorbed making it an endothermic reaction.
The Carousel Activity showed us different types of physical and chemical changes. It also helped distinguish between
what constitutes a physical versus chemical change.
2) Taking up the Carousel activity
Station
Action
Observation
Physical Change
Chemical Change
1) Soda Can
Crushing of
the soda can
Change of shape
Yes
No
2) Glow Sticks
Crack the
glow sticks
The sticks glow
No
Yes
3) Ice Cubes
Melting of the
ice
Water is formed
from the ice
melting
Yes
No
4) Icepack
Breaking the
icepack
Cold is created
when pouch is
broken
No
Yes
5) Water and Salt
Adding Salt to
Water
Will create a
cloudy look to
the water
Yes
No
6) Vinegar and
Baking soda
Adding Baking
soda to
vinegar
Will cause
bubbles to form
No
Yes
12
3) Description of a physical change:
“Occurs when an object or substance undergoes a change in physical properties but maintains its chemical properties”
-
Physical Properties: texture, shape, size, colour, volume, mass, weight, taste, smell, density
 Description of a chemical change:
“Occurs when an object or substance is changed or altered, creating a new substance and an energy change
(exothermic: releases energy i.e. explosion or endothermic: system absorbs energy i.e. cold pack)”
-
Chemical Properties: burning, decomposition, neutralization, cooking, oxidation, ripening, combustion
Law of Conservation of Mass and Chemical Equations
4 & 5) The Law of Conservation of Mass
“In a chemical reaction, the mass of the products always equals the mass of the reactants”
 To demonstrate this, teacher will use the small, plastic atoms to show that each atom is conserved throughout the
reaction
All chemical reactions have reactants and products
-
Reactants are always found on the left side of the equation, and react together to form the Products, which are
always found on the right side of the equation
The mass of the atoms on the reactant side must always equal the mass the of atoms on the product side of the
equationthis adheres to the Law of Conservation of Mass
The number of atoms also stays the same in each equation
13
Appendix B2.1 - Action
Chemical and Physical Changes, Chemical Equations and Conservation of Mass Handout
1) What did the activities that we just completed demonstrate to us about physical and chemical reactions?
The Egg Experiment:
The Carousel Activity:
2) Now, lets take up the Carousel Activity. Together, we will fill in the action and result of the change, and whether it
was a physical or chemical change.
Station
Action
Result
Physical
Change
Chemical
Change
1) Soda Can
2) Glow Sticks
3) Ice Cubes
4) Icepack
5) Water and
Salt
6) Vinegar and
Baking soda
14
3) Describe the properties of the following and give an example of each:
1) A physical change:
2) A chemical change:
4) What is the Law of Conservation of Mass? Why is it important with regards to chemical equations?
5) What are the elements on the left side of a chemical equation called? The right side?
15
Appendix B3.0 - Action
Law of Conservation of Mass Worksheet
Instructions:
* Fill out the reactants and products/ equations in the spaces provided.
* Look at the reactants and in the space provided write out the number of atoms for each element. Do the same for the
products.
* Weigh the reactants on the scale and record the mass. Do the same for the products.
Equation
Reactants (R)
Number
of atoms
in R
Mass
of R
Products
(P)
Number
of atoms
in P
Mass
of P
C2 + O2 + O2 CO2 +
CO2
H2 + H2 + O2
H2O + H2O
6CO2 + 6H2O
C6 H12 O6 +
6O2
CH4 + 2O2  CO2
+2H2O
2H + CO3  H2O + CO2
What do you notice about the number of atoms in the reactants and the products of the same chemical equation? What
of you notice about the mass?
16
Appendix B3.1 - Action
Law of Conservation of Mass Worksheet – Answer Key
Instructions:
* Fill out the reactants and products/ equations in the spaces provided.
* Look at the reactants and in the space provided write out the number of atoms for each element. Do the same for the
products.
* Weigh the reactants on the scale and record the mass. Do the same for the products.
Equation
Reactants (R)
Number
of atoms
in R
Mass
of R
Products
(P)
Number
of atoms
in P
Mass
of P
C2 + O2 + O2 --> CO2 +
CO2
C2 + O2 + O2
O= 4
C= 2
N/A
CO2 + CO2
O= 4
C= 2
N/A
H2 + H2 + O2 --> H2O +
H2O
H2 + H2 + O2
H= 4
O= 2
N/A
H2O + H2O
H= 4
O= 2
N/A
CH4 + 2O2 --> CO2
+2H2O
CH4 + 2O2
C= 1
H= 4
O= 4
N/A
CO2 + 2H2O
C= 1
H= 4
O= 4
N/A
2H + CO3 --> H2O + CO2 2H + CO3
H= 2
O= 3
C= 1
N/A
H2O + CO2
H= 2
O= 3
C= 1
N/A
6CO2 + 6H2O --> C6 H12
O6 + 6O2
C= 6
O= 18
H= 12
N/A
C6 H12 O6 +
6O2
C= 6
O= 18
H= 12
N/A
6CO2 + 6H2O
What do you notice about the number of atoms in the reactants and the products of the same chemical equation? What
of you notice about the mass?
The number of atoms in the reactants is the same as the number of atoms in the products.
The mass of the reactants are equal to the mass of the products.
17
Appendix C1.0 – Consolidation & Connection
Chemical Reactions that Affect our Environment Homework Sheet
Combustion is an example of a chemical reaction that occurs abundantly on our planet. Unfortunately, there
are many types of combustion reactions that negatively contribute to air pollution and greenhouse gas production.
Combustion can occur in two forms:
1) Complete combustion
- Occurs when the reactants burn completely in oxygen, and the products created are an oxide and water
(H20)
- An oxide can be created from many elements, but the most common oxide in combustion reactions is
Carbon Dioxide (CO2), which is formed when any hydrocarbon is burned. The formula for a
hydrocarbon being burned is as follows: CH4 + 2 O2 → CO2 + 2 H2O
- Other common involved are Nitrogen, Sulphur and Iron, which also produce oxides.
2) Incomplete Combustion
- Occurs when there is not enough oxygen to fully oxidize (burn) the reactants to produce CO2.
- As a result, Carbon Monoxide (CO) is produced when a hydrocarbon is burned, along with CO2, H2O and H2
Ideally, all combustion reactions would be complete reactions, meaning that all reactants are fully oxidized and
burned. However, the majority of these reactions that occur in our world are incomplete, resulting in other harmful
products being created. As we can see, the burning of hydrocarbons can create dangerous and harmful greenhouse
gases that are damaging to our environment. Some of the products created when these reactions happen are as follows:
1)
2)
3)
4)
5)
6)
Ozone- causes smog and many healthy issues especially in the lungs. It also affects trees and plants,
which are crucial to the life cycle
Volatile Organic Compounds (VOCs) – these chemicals are cancer-causing agents.
Nitrogen Dioxide (NO2) – causes smog and acid rain, and damages trees and buildings.
Carbon Monoxide – causes a number of related health illnesses
Chlorofluorocarbons (CFCs) – these damage the ozone layer and causes numerous health problems
Carbon Dioxide (CO2) – a main ingredient in global warming, as it collects heat and light that is given
off from the sun.
Choose THREE of the six products produced from combustions reactions shown in the list above. For each of the THREE
you have chosen:
1. Give an example of how they are released into our environment.
2. What are some measures our society can take to reduce the amount of these by-products released in our
atmosphere?
3. What are some of the measures that YOU can take to reduce the amount of these by-products?
18
“Remember that life's A Great Balancing Act. And will you succeed? Yes! You will, indeed! (98 and ¾
percent guaranteed) Kid, you'll move mountains.”
― Dr. Seuss, Oh, the Places You'll Go!
NAMES: Kalvin Lau & Holly Wykes
UNIT: Chemical Reactions
TITLE OF LESSON: Writing Balanced Chemical Equations
BIG IDEAS:
MATERIALS:
- Chemicals react with each other in
- Lego Bricks
predictable ways
- Weight Scale
- Chemical reactions may have a negative
- Balancing Chemical Equations Chart
impact on the environment, but they can
also be used to address environmental
(1 per student)
challenges.
- Molecular Model Kits
MINISTRY EXPECTATIONS:
(1 per group of 4-5 students)
- A1.12 Use appropriate numeric, symbolic,
- Balancing Chemical Equations Activity
and graphic modes of representation, and
(1 per student)
appropriate units of measurement (e.g., SI
and imperial units)
- A1.13 Express the results of calculations
involving data accurately and precisely
- C2.2 Construct molecular models to
illustrate the structure of molecules in
simple chemical reactions (e.g., C + O2 
CO2; 2H2 + O2  2H2O), and produce
diagrams of these models [PR, C]
- C3.4 write word equations and balanced
chemical equations for simple chemical
reactions (e.g., 2H2 + O2  2H2O)
STUDENT LEARNING GOALS:
APPENDICES:
1. Understand basic definitions including
A1.0 Minds-on Activity: Teaching Notes
reactant, product, subscript and
A1.1 Minds-on Activity: Chalkboard Notes
coefficient.
B1.0 Intro to Balancing Chemical Equations:
2. Understand the difference between a
Teaching Notes
skeleton chemical equation and a
B1.1 Intro to Balancing Chemical Equations:
balanced chemical equation.
Student Handout
3. Construct, using molecular model kits,
B1.2 Intro to Balancing Chemical Equations:
reactants and products to create balanced Chalkboard Notes
chemical equations.
B2.0 Molecular Model Kits: Teaching Notes
4. Successfully complete the steps to balance B2.1 Molecular Model Kits: Chalkboard Notes
written skeleton equations.
B3.0 Balancing Chemical Equations Activity:
5. Apply knowledge of chemical equations to Teaching Notes & Solutions
environmental challenges.
B3.1 Balancing Chemical Equations Activity:
Student Handout
PRIOR KNOWLEDGE:
C1.0 Oil Spill Application: Teaching Notes
Definitions and examples regarding: Matter and
C1.1 Oil Spill Application: Chalkboard Notes
the Periodic Table; Ions, Molecules and
Compounds; Chemical Reactions; Law of
Conservation of Mass
19
A
MINDS ON
5-10 mins
B
ACTION
20-25 mins
15-20 mins
15-20 mins
C
CONSOLIDATION &
CONNECTION
T/L STRATEGIES:
1) Conservation of Mass Demo
Show sample of Lego bricks.
Demonstrate how pieces combine to
create a new structure. How does
this relate to Conservation of Mass?
Appendix A1.0
1) Introduction to Balancing
Chemical Equations Chart
Give example skeleton equation and
show how to balance using
coefficients and Law of Conservation
of Mass. Fill in chalkboard chart
showing steps to balancing a
skeleton chemical equation.
Appendix B1.0; B1.1; B1.2
2) Molecular Model
Construction:
In groups of 4-5, students construct
reactants and products using
Molecular Model kits and
demonstrate correctly balanced
models.
Appendix B2.0; B2.1
3) Balancing Chemical
Equations Activity:
Independently, students complete a
problem-solving handout quizzing
definitions and correct balancing of
chemical equations.
Appendix B3.0; B3.1
1) Oil Spill Clean-up
Application:
Discussion of how chemicals can be
added to oil spills to neutralize
toxicity in environment.
RATIONALE:
Allow students to recall
the topic and think
about applications of
Conservation of Mass.
ASSESSMENT:
Predict/Observe/
Explain,
Think/pair/share.
Introduce concept of
balancing chemical
equations using
coefficients and
demonstrate correct
method of solving
skeleton equations
using chart on
chalkboard.
Allows students to
visualize skeleton and
balanced chemical
equations, provide
practice of balancing
chemical equations
using 3-dimensional
models.
Participation in
discussion, correct
answers to fill out
chalkboard chart.
Provides individual
practice of basic
definitions and problem
solving regarding
balancing chemical
equations.
Correct answers as a
group, taken up in class
to consolidate learning.
Applies application and
analysis of learned
concepts to real-life
examples, solidify
importance of balanced
chemical equations.
Think/pair/share,
discussion format in
class, contributions to
filling out chart.
Presentation of
correctly balanced
chemical equations,
explanation to
classmates, filling in
correct coefficients on
chalkboard.
5-10 mins
NEXT
STEPS
Appendix C1.0; C1.1
- Strategies for Balancing Chemical Equations
- Chapter Quiz
- Introduction to Acids and Bases (next unit)
20
Appendix A1.0 Minds-on Activity – Teaching Notes
-
Purpose: demonstrate the law of conservation of mass.
Display of scale and unassembled Lego model at front of class.
Unassembled bricks represent reactants and the assembled model will represent the products – items can be
substituted with other materials of similar concept e.g. puzzle
Questions to ask:
“We have Lego bricks here, how much do you think they weigh? Let’s see how much they weigh.”
Weigh bricks and record in table
Predict: “After we assemble the model, do you think it will weigh more or less than the parts?”
Observe: Weigh the assembled model and record in table
“What if we had enough parts to make a few cars? Would the parts weigh more than the assembled cars?”
Weight two sets of unassembled bricks. Record in table.
Assemble the bricks and weight again. Record in table.
Explain: “What did you notice? Why does this happen?”
Weigh reactants and then assemble model and weight product. Demonstrate they are the same weight. Review
the law of conservation of mass
The mass of substances produced (products) by a chemical reaction is always equal to the mass of the reacting
substances (reactants)
21
Appendix A1.1 Minds-on Activity – Chalkboard Notes

Weight of items (g)
Unassembled bricks
Assembled bricks
1set
2 sets
22
Appendix B1.0 Introduction to Balancing Chemical Equations – Teaching Notes
-
The rearrangement of atoms that occurs during a chemical reaction can be illustrated using models or diagrams.
-
E.g. Hydrogen + Oxygen  Water
-
To balance a chemical reaction, we need to apply the Law of Conservation of Mass:
In a chemical reaction, the mass of the products always equals the mass of the reactants.
-
In the formula for this reaction, there has to be equal numbers of hydrogen atoms and oxygen atoms on both
the reactants and products side.
-
When the number of each kind of atom is the same in reactants and products, the equation is said to be
balanced.
-
The equation on the board is a skeleton equation; that is, the names of the elements are correct, but the
numbers of each differ on the reactants and products sides of the equation.
-
To reach the correct number of elements on each side of the equation, add coefficients to the reactants and
products to change the ratio of each within the equation.
-
Note that the subscripts do not change as these indicate the ratio of elements within each formula.
-
E.g. 2H2 + O2  2H2O
H2 + O2  H2O
23
Teaching Notes (Cont’d) – Filling in the Chart
Balance the following chemical equation:
AlBr3 + Cl2  AlCl3 + Br2
1. Count the number of atoms of each element in the skeleton equation.
Reactants
AlBr3
Cl2
Number of Atoms
Al = 1
Br = 3
Cl = 2
Products
AlCl3
Br2
Number of Atoms
Al = 1
Cl = 3
Br = 2
2. Balance the number of bromine atoms by adding a coefficient of 2 in front of AlBr3 and a coefficient of 3 in front
of Br2. Count the number of atoms again by multiplying the coefficient by the number of atoms in the formula.
Reactants
2AlBr3
Cl2
Number of Atoms
Al = 2 x 1 = 2
Br = 2 x 3 = 6
Cl = 2
Products
AlCl3
3Br2
Number of Atoms
Al = 1
Cl = 3
Br = 2
3. Balance the number of aluminum atoms by adding a coefficient of 2 in front of AlCl3. Count the atoms again.
Reactants
2AlBr3
Cl2
Number of Atoms
Al = 2 x 1 = 2
Br = 2 x 3 = 6
Cl = 2
Products
2AlCl3
3Br2
Number of Atoms
Al = 2 x 1 = 2
Cl = 2 x 3 = 6
Br = 3 x 2 = 6
4. Balance the number of chlorine atoms by adding a coefficient of 3 in front of Cl2. Count the atoms again.
Reactants
2AlBr3
3Cl2
Number of Atoms
Al = 2 x 1 = 2
Br = 2 x 3 = 6
Cl = 3 x 2 = 6
Products
2AlCl3
3Br2
Number of Atoms
Al = 2 x 1 = 2
Cl = 2 x 3 = 6
Br = 3 x 2 = 6
The equation is now balanced:
2AlBr3 + 3Cl2  2AlCl3 + 3Br2
24
Appendix B1.1 Introduction to Balancing Chemical Equations – Chalkboard notes
Chalkboard 1 – Steps
1. Count element atoms in both reactants and products.
2. Select an element to balance that is not hydrogen or oxygen, e.g. Bromine. Add coefficients to compounds and
elements that contain Bromine and then count atoms again.
3. Balance the next element by adding coefficients to compounds containing element, e.g. Aluminum and count
atoms again.
4. Balance next element that is not balanced yet, e.g. Chlorine. Add coefficients to compounds or elements that
contain Chlorine. Count the number of element atoms.
5. Continue process until all elements are balanced. Once all elements are balanced, the equation is complete.
Recount the atoms to double check your work.
Chalkboard 2 – Chart
Skeleton Equation: AlBr3 + Cl2  AlCl3 + Br2
Reactants
AlBr3
Cl2
Number of Atoms
Products
AlCl3
Number of Atoms
Br2
25
Appendix B1.2 Introduction to Balancing Chemical Equations – Student Handout
Balance the following chemical equation:
AlBr3 + Cl2  AlCl3 + Br2
1. Count the number of atoms of each element in the skeleton equation.
Reactants
Number of Atoms
Products
Number of Atoms
2. Balance the number of bromine atoms by adding a coefficient of 2 in front of AlBr3 and a coefficient of 3 in front
of Br2. Count the number of atoms again by multiplying the coefficient by the number of atoms in the formula.
Reactants
Number of Atoms
Products
Number of Atoms
3. Balance the number of aluminum atoms by adding a coefficient of 2 in front of AlCl3. Count the atoms again.
Reactants
Number of Atoms
Products
Number of Atoms
4. Balance the number of chlorine atoms by adding a coefficient of 3 in front of Cl2. Count the atoms again.
Reactants
Number of Atoms
Products
Number of Atoms
26
Appendix 2.0 Molecular Model Kits – Teaching Notes
1. Divide class into groups of 4-5.
2. Provide each group with one Molecular Model Kit.
3. Ask each group to construct one of the following skeleton equations:
a.
b.
c.
d.
e.
H2 + O2  H2O
Na + O2  Na2O2
CO2 + H2O  H2CO3
N2 + H2  NH3
Fe + Cl2  FeCl3
4. Ask each group to balance the constructed skeleton equations by building additional molecules as needed.
5. A volunteer from each group will present their findings in molecular model form.
6. A volunteer from each group will fill in any coefficients needed to balance the skeleton equations as written on
the blackboard.
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Appendix B2.1 Molecular Model Kits – Chalkboard Notes
a. 2H2 + O2 2H2O
b. 2Na + O2  Na2O2
c. 2CO2 + 2H2O 2H2CO3
d. N2 + 3H2  2NH3
e. 2Fe + 3Cl2  2FeCl3
28
Appendix B3.0 Balancing Chemical Equations Activity – Teaching Notes
1. Give each student one handout face down on the desks.
2. Ask each student to work independently to answer the questions to the best of their ability.
3. Be sure to erase the chalkboard notes!
4. Allow 15-20 minutes to complete the activity.
Answer Key:
1. A skeleton equation is an equation showing the reactants and products in their molecular state. A balanced
equation uses coefficients to apply the Law of Conservation of Mass to the equations and contains the same
number of atoms on both sides of the equation.
2. A subscript gives the ratio of elements in a formula; they cannot change in a given chemical. A coefficient gives
the ratio of the reactants and products in the reaction; thus are used to balance chemical equations.
3.
a.
b.
c.
d.
e.
f.
2H2 + O2  2H2O
4Na + O2  2Na2O2
2CO2 + 2H2O  2H2CO3
N2 + 3H2  2NH3
2Fe + 3Cl2  2FeCl3
CH4 + 2O2  CO2 + 2H2O
4.
a. 2C8H18 + 25O2  16CO2 + 18H2O
b. 25 carbon dioxide molecules
29
Appendix B3.1 Balancing Chemical Equations Activity – Student Handout
1. What is the difference between a skeleton equation and a balanced equation?
2. What is the difference between a subscript and a coefficient in a chemical equation?
3. Balance the following skeleton equations:
a. H2 + O2  H2O
b. Na + O2  Na2O2
c. CO2 + H2O  H2CO3
d. N2 + H2  NH3
e. Fe + Cl2  FeCl3
f. CH4 + O2  CO2 + H2O
4. Octane, C8H18, is a compound in gasoline. Octane burns in oxygen to produce carbon dioxide gas and water
vapour.
a. Write a balanced chemical equation for this reaction.
b. How many carbon dioxide molecules are produced for every molecule of octane burned?
30
Appendix C1.0 Oil Spill Application – Teaching Notes
Introduce the concept of environmental application for the use of balancing chemical equations.
One of the ways in which environmental workers clean up oil spills is by adding another chemical to the spill to
neutralize the toxicity of the pollutants. Using the knowledge obtained regarding the Law of Conservation of Mass and
balancing chemical equations:
1. What might happen if too little neutralizing chemical is added to an oil spill?
2. What might happen if too much neutralizing chemical is added to an oil spill?
3. What could be the effects of an oil spill that is not attended to?
To be completed in a Think/Pair/Share format.
Ask students to write their responses in the chart.
31
Appendix C1.1 Oil Spill Application – Chalkboard Notes
Too Little Chemical
More reactant (oil) than
product (neutral
substance)
- Not all oil is neutralized,
toxicity remains
-
Too Much Chemical
More reactant
(neutralizing substance)
remains
- Neutralizing substance
could pose additional
environmental threat i.e.
if toxic on its own
-
Unattended to Spill
Toxicity may affect plant,
animal, aquatic life
- Altered pH of water
where oil is spilled
-
32