Chemical Reactions: Grade 8
California Science
Content Standards
NGSS
Lesson Overview
Time Frame
Grade Level
P.S. #5 Chemical reactions are processes in which atoms are rearranged into
different combinations of molecules.
5a. Students know reactant atoms and molecules interact to form products
with different chemical properties.
5c. Students know chemical reactions usually liberate heat or absorb heat.
MS-PS1-6 Students who demonstrate understanding can undertake a design
project to construct, test, and modify a device that either releases or absorbs
thermal energy by chemical processes.
Students will explore chemical reactions by mixing calcium chloride, baking
soda, and phenol red. They will then use calcium chloride to design and
create a hot pack. This is designed to be a cumulating activity after students
have already observed and studied physical and chemical changes as well as
exothermic and endothermic reactions. The Engage portion can be altered
slightly and used at the beginning of the unit.
Engage – ½ - 1 day (55 minute class period)
Explore – 1 day (55 minute class period)
Explain – 1/2 day (55 minute class period) or homework
Elaborate (Super structured) – 1 day (55 minute class period)
Elaborate (Less structured) – 2-3 days (55 minute class periods)
Evaluate (lab report) – Homework (~1 week)
8th grade Physical Science
Lesson Plan Day 1
Teacher asks/says/does:
Student asks/says/does:
Students
will
recognize
and
cite
evidence
of
physical changes and chemical
Specific Learning Objectives
Materials
Vocab
Engage
Students make observations
as they mix calcium
chloride, baking soda, and
phenol red.
reactions taking place.
calcium chloride
phenol red solution
graduated cylinder
physical change
precipitate
*NOTE: It is much more effective to
have the all the groups do this part at
the same time. If some groups are
ahead of the others, it lessens the
excitement for the other groups. I do
this activity in groups of four.
Today you will be creating and
observing physical and chemical
changes. What is a physical change?
(Knowledge)
What is a chemical change?
(Knowledge)
What are some examples of evidence
that a chemical reaction has
occurred?
(Knowledge)
baking soda
re-sealable plastic bag
film canister or test tube (optional)
chemical change
chemical reaction
Students should answer that a
physical change can be any change
to the size, shape, or state of matter
in which the identity of the
substance does not change. During a
physical change a new substance is
NOT created.
Students should answer that during a
chemical change a new substance is
created.
-
color change
temperature change
precipitate formation
gas production (bubbles
without boiling)
As the students answer this question,
write the answers on a lab sheet
under the document camera
You will now make observations of
the chemicals that we will be using.
Before I pass out the chemicals there
are a few safety considerations. First
of all, safety goggles must be worn
starting now and until EVERY group
has returned their lab materials.
Second, you may NOT touch, eat,
drink, or taste any of the lab
materials. (At this point I love to
read the safety cautions on the
Calcium Chloride bottle). If you
want to smell the chemicals,
remember to waft. Finally, you may
NOT mix any chemicals together
unless I explicitly tell you to do so.
All the mixing of chemicals will take
place in Ziploc bags – NOT in any of
the containers. Left over materials
will be used for other class periods.
Trust me, I will know if you mix
things at the wrong time or in the
wrong place!
Ok, who can tell me the safety rules?
(Knowledge)
new properties
Students list the evidence on their
lab sheet.
Students put on their safety goggles.
Students should repeat the rules.
When you receive your materials,
you will make careful observations
of each chemical. Be sure to be as
descriptive as possible. You are
NOT going to mix anything yet.
Pass out the materials. I like to have
everything on a tray with all the
chemicals labeled.
Students get their materials and
make observations.
For this activity, every group is
going to do each step at the same
time so you need to wait for my
instructions.
1.
2.
3.
4.
Put 1 teaspoon of baking
soda in the plastic bag.
Put 2 teaspoons of calcium
chloride into the same bag
and mix.
Use the graduated cylinder
to measure 10mL of phenol
red solution.
Pour the phenol red into the
Students follow all steps of the
procedure.
5.
6.
film canister
Carefully put the canister of
phenol red into the bag
without tipping it and seal
the bag
When the bag is fully
sealed, tip the canister to
mix the chemicals and
observe. (NOTE: Steps 4 - 6
are optional. The students
can also pour the liquid
directly into the bag and
seal it quickly)
Please write down a detailed
description of what you observed.
The bag will expand, the color will
turn yellow, and it will get hot.
Students write down a detailed
description of what they observed
NOTE: If they did not mix well parts
might feel cold (baking soda and
water is endothermic). This is why
they use more calcium chloride than
baking soda)
Which of these changes is evidence
of a chemical change? (Evaluation)
To clean up, bring all your materials
to the front. Do NOT open your
baggies.
Science Process Skills used (if
applicable):
How is student participation
ensured?
Students should say color change,
gas production, temperature change,
new properties. They should
underline these on their lab sheet.
Students bring up their materials.
NOTE: You may wash and reuse the
bags if desired or you can throw
away all the materials.
Observing
Following a procedure
Analyzing data
 Walk around while they are making their observations to ensure
that all students are completing this section. Emphasize that you
will not move on to the experiment until EVERYONE has
completed their observations
 Divide the tasks for the activity so that each group member has a
specific role.
All students should get to feel the baggie after the experiment has taken
place.
Lesson Plan Day 2
Teacher asks/says/does:
Student asks/says/does:
Specific Learning Objectives Students will design and perform a series of mini-experiments to determine
Materials
Explore
the combination of chemicals responsible for each change that occurred.
calcium chloride
baking soda
phenol red solution
re-sealable plastic bag
graduated cylinder
water
NOTE: This activity can be done on
the same day as the Engage activity
if your students are VERY efficient
Students design miniexperiments to determine
which components of the
previous lab are responsible
for creating heat.
and self-motivated. If it is your first
time doing these labs, I would
recommend spending two days. If
you have time on day 1, you could
have students plan their experiments
and then perform the experiments on
day 2.
Yesterday you observed a chemical
reaction. Today you are going to
design experiments to test which
chemicals were responsible for each
chemical change that you observed.
In your groups design a set of
procedures to see what happens
when you test 2 or 3 chemicals at a
time. The phenol red solution is
made by mixing phenol red powder
and water so you may use water in
your experiments. Be sure to keep
the amounts the same. For example,
you will only use 1 teaspoon of
baking soda or 10 mL of water.
Everyone in your group should have
the same procedures in the same
order!
Students write their procedures.
Once you have written your
procedures and I have checked them,
I will give you the supplies to
perform your experiments.
Remember the same safety rules
apply. Also, you will need to put on
your safety goggles as soon as the
first group gets their materials even
if your group is still working on
writing your procedure.
Check their procedures. They should
have the following:
1. 1 tsp. baking soda + 10 mL
phenol red
2. 1 tsp. baking soda + 10 mL
water
3. 2 tsp. calcium chloride + 10
mL phenol red
4. 2 tsp. calcium chloride + 10
mL water
5. 1 tsp. baking soda + 2 tsp.
calcium chloride + water
Science Process Skills used:
Designing an experiment
Performing an experiment
Students see the following results:
1. cold, pink
2. cold
3. hot, pink
4. hot
5. hot, gas production
How is student participation
ensured?



Emphasize that you will not each group to complete their
experiments until EVERYONE in the group has written down their
procedures
Divide the tasks for the activity so that each group member has a
specific role.
Walk around while they are making their observations of their
results to ensure that all students are completing this section.
Lesson Plan Day 3
Teacher asks/says/does:
Student asks/says/does:
Specific Learning Objectives Students will list and explain examples of physical changes, chemical
Materials
Vocab
Explain
Students define the terms
physical change, chemical
change (chemical reaction),
exothermic reaction,
endothermic reaction, and
apply them to their
experiments. They will also
research hot packs.
changes, exothermic reactions, and endothermic reactions
Chemical Reactions Lab Worksheet
Internet access or Handouts with
Hot pack research questions
information about hot packs
physical change
chemical change
Note: This can be done on the same
day as the “Explore” lesson or on the
following day.
exothermic reaction
endothermic reaction
In your own words, please define
physical change, chemical change,
exothermic reaction, and
endothermic reaction.
(Comprehension) Then give
examples that you observed in the
lab. Be sure to explain your
examples. (Analysis)
A physical change can be any
change to the size, shape, or state of
matter in which the identity of the
substance does not change. During a
physical change a new substance is
NOT created.
NOTE: This can be done as a class
discussion, small group discussion,
or individually either in class or for
homework.
A chemical change a new substance
is created.
An exothermic reaction releases heat
(feels hot).
An endothermic reaction absorbs
heat (feels cold).
Mixing the baking soda and calcium
chloride is a physical change.
Mixing Phenol Red powder with
water is a physical change.
Mixing baking soda and water and
baking soda and Phenol Red are
chemical changes and are
endothermic.
Mixing calcium chloride with water
or phenol red is a chemical change
and is exothermic.
NOTE: This part can be done for
homework if students have access to
the internet. If not, you can print out
information and have the students
complete their research in class.
Use the internet to answer the
following questions. List your
source(s) next to each of your
answers. Do NOT use wiki.answers,
ask.com, etc.
1.
2.
3.
Science Process Skills used:
How is student participation
ensured?
What are hot packs?
Why are they used?
How do they work?
Research
Analysis
 Walk around while they are working to ensure that all students are
completing this section.
 If doing this as a group discussion, have students do a “think, pair,
share” for each question and then randomly call on students.