LESSON PLAN TEMPLATE – Classroom Interactions
Big Idea/ Enduring Understanding for the lesson:
Stoichiometry: Law of Conservation of mass, qualitative experiment
TEKS for lesson:
(6) Science concepts. The student knows and understands the historical development of atomic theory. The student is expected to:
(E) express the arrangement of electrons in atoms through electron configurations and Lewis valence electron dot structures.
(7) Science concepts. The student knows how atoms form ionic, metallic, and covalent bonds. The student is expected to:
(C) construct electron dot formulas to illustrate ionic and covalent bonds;
(8) Science concepts. The student can quantify the changes that occur during chemical reactions. The student is expected to:
(D) use the law of conservation of mass to write and balance chemical equations; and
(E) perform stoichiometric calculations, including determination of mass relationships between reactants and products
(10) Science concepts. The student understands and can apply the factors that influence the behavior of solutions. The student is expected to:
(A) describe the unique role of water in chemical and biological systems;
Objective/s- Write objective/s in SWBAT
form…
The SWBAT:
Assessment:
Completed worksheets, participation in discussion, and analysis of
predictions.
Formative during lab time.
Overview of Activities:
15-20min: Introduction/Review/Vocabulary – Explain or review concepts of stoichiometry. [Coefficients, subscripts,
reactants/products, reverse reactions, association/dissociation, Law of Conservation of Mass.]
25-35min: Experiment – Splitting of water using electrochemistry. [No knowledge of electrochemistry needed.] Qualitative
explanation of stoichiometry, standard states, and use of experimental design and lab ethic.
10-15min (or assigned homework): Analysis/Discussion of results – Visible products explain stoichiometry.
LESSON EPISODES (In segments. No set number.)
Estimated
Time
~1520min
Segment
title/
description
Introductio
n and real
world
application
What teacher is doing step by step (Include specific
questions that the teacher will ask as well as
sample problems)
What students are doing (consider transitions to the next
segment and grouping)
Present students with the concepts behind
baking. Set up an “equation” with the
ingredients, the reactants, of chocolate chip
cookies added together to get an x amount of
cookie products.
ex: _eggs+_flour+_sugar+_chocolate
chips+_butter->_cookies
Students are taking notes in their designated spirals or
folders.
Start with stating that basic amount of
ingredients that make 12 cookies. Fill in the
blanks appropriately, they do not have to exact
it’s all hypothetical, and explain the use of the
coefficients. [Make sure to note that the
reaction can happen in reverse, cookies can be
‘dissociated’ to regain the reactants. Not
always true for all equations but for the sake of
this example it could be helpful.]
Teacher: So I want to make x amount of cookies. What
would I do if I wanted to get x amount of eggs? X
amount of sugar?
Student: Go backwards?
Divide?
That’s impossible.
Teacher: Maybe when making cookies, but a lot of
chemical equations can actually go in reverse.
Coefficients are the numbers next to a reactant
or product that tells how many are needed or
created for a reaction.
Once this is understood, the class should have
a brief grasp on reactants, products, and
coefficients. Then explain what would happen
to the reactants if we only made 6 cookies? 24
cookies? 18 cookies? Let the students think
pair share at their tables or with a partner for
about 3 minutes and ask one student from
Teacher: What happens to the number of reactants as
the number of products are reduced?
Student: There are less than before.
They also decrease.
It would stay the same, you would just have
extra dough.
each different group (3 total) to come to the
board and show their answer. This will spark
discussion of how the amount of product can
be controlled by the amount of reactants.
To introduce subscripts, replace sugar with
actual chemical formula of glucose in the
recipe.
_eggs+_flour+_C6H12O6+_chocolate
chips+_butter->_cookies
Explain how the coefficient is then multiplied
throughout each element if that element has
any. For any without subscripts, it is assumed
there is only one of those elements.
End introduction by presenting real chemistry
equations and starting discussion of how we
can see how much product is getting made.
Since the product isn’t as visible as the number
of cookies that change, there has to exist some
knowledge about the components of the
reactants and equation. Bring up Law of
Conservation of Mass. (Should be review.)
Some example equations:
𝑁𝐻4 ↔ 𝑁𝐻3 + 𝐻 +
6𝐶𝑂2 + 6𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2
Allow students to then work on Supplement A.
(~5min)
Resources
for this
segment &
Teacher: What is the subscript?
Student: The number that comes after the element
The subscript identifies the molecule.
Teacher: What is the coefficient?
Student: The number before the molecule
The coefficient identifies how many molecules
are present.
Teacher: What is the difference between a coefficient
and a subscript?
Student: You can change the coefficient, but you cannot
change the subscript
Terms to know: Word bank could be used here.
 dissociation
 association/synthesis/recombination
 coefficients
 reactants
 products
 reverse reaction
 subscripts
 Lass of Conservation of Mass
Supplement A worksheets, chalkboard/whiteboard/doc cam. Optional: Word bank, actual cookies for engagement.
SAFETY
considerati
ons
~3035min
Water
splitting
experiment
The reaction of interest today is the splitting, or
dissociation of water into its original elements.
_𝐻2 𝑂(𝑙) ↔ _𝑂2 (𝑔) + _𝐻2 (𝑔)
Make note of the physical states of water and
hydrogen and oxygen. Also make note of the
double headed arrow to show that it is a
reversible reaction.
Sort students into their lab groups. Explain that
the stoichiometry of this equation is incomplete
and the lab today will show qualitatively how
this reaction proceeds. Before students can be
released to start the lab, they must preset their
finished balanced reaction to show their
understanding of how coefficients work. They
must also predict what they think will show in
the experiment. [This can be variable, just
allows students to make their own ideas and
assumptions. Right or wrong still helps
understanding after experiment.]
Teacher: Does anyone know the reaction for the
association or dissociation of water? What is the
reaction? [Either form is applicable.]
Student: It’s made up of hydrogen and oxygen.
You can’t split water, it’s pure.
Teacher: If we can agree that hydrogen and oxygen
make up water, how would I write that equation?
Student: 𝐻2 𝑂 → 𝐻 + 𝑂 (Just one possible misconception.)
Teacher: Can hydrogen and oxygen simply exist as lone
elements though? What do we know about standard
states of elements?
Student: Oxygen and hydrogen exist as diatomic gases
in their standard states.
Teacher: Show assigned lab groups/tables. Preferable
with 3 or less in each group. In your lab notebooks,
decide in your groups the correct final equation and
make a prediction, at least 2 sentences, about what you
think you will see. [Pass out supplement B at lab
tables.]
Student: If we’re making gases, how can we see the
products?
Teacher: I’m glad you asked, here we have a short
video to show the lab. [Show youtube video, make sure
to not show results.]
Present YouTube video
Using the supplement B as a guide and the
video as background, the lab groups should be
able to follow the instructions. Trouble may
Teacher: Make sure to take observations and notes of
anything you may think are important!
occur in filling up the vials with water, so help
may be needed. Other steps should not need
much assistance.
Resources
for this
segment &
SAFETY
considerati
ons
~1015min or
homework
Supplement B worksheets, lab notebooks for observations/predictions, YouTube video, lab kits, outlets (12V adapters),
water, 500mL beakers, sodium sulfate (20g per kit), and clip leads. Goggles mandatory. Gloves optional.
Go over lab safety rules:
 Goggles AT ALL TIMES, no exceptions!
Hydrogen is safe in quantities generated in this experiment (<15mL) and will dissipate without effect, but H 2 should not be
generated in any great quantity than that suggested here!
Analysis/
Discussion
Have students close down lab, should take less
than five minutes. Return to desks and have
them answer analysis questions. Can be used
as an exit ticket or as assigned homework.
If assigning analysis as homework, start class
discussion. If students are confused or
struggled too much with lab, it is preferred to
end with discussion so they have basis to
answer the homework. Any misconceptions or
questions should be answered.
Some example discussion topics are listed.
Could be more in depth with stoichiometry and
law of conservation of math. Take which
direction the class is lacking in.
DISCUSSION:
Teacher: I need to someone to come write their
equation on the board that they used in their
experiment.
Student: If they write the correct equation, ask if
anyone got a different answer. If they did, ask other
class members what is different. If they write the
incorrect equation, ask another student to write their
equation too. There shouldn’t be much variation, but
having multiple students write on the board will put less
emphasis on the student that may have been wrong.
Teacher: So the correct final equation is –
2𝐻2 𝑂(𝑙) ↔ 𝑂2 (𝑔) + 2𝐻2 (𝑔)
How many of each element are there on each side?
Remember that products must equal reactants.
For advanced classes: Have students write a
full lab report. With abstract, experimental
design, results and conclusion.
Resources
for this
segment &
SAFETY
considerati
ons
Student: 4 hydrogen and 2 oxygen.
Teacher: In comparison to oxygen molecules, how many
more hydrogen molecules are there?
Student: There are two more hydrogens.
Hydrogens are double the amount of oxygen.
Teacher: Did we see this in the experiment? Can
someone explain what they saw?
Student: There was more gas in one tube than in the
other.
It looked about twice as much.
I couldn’t really tell.
Teacher: So we agreed that our equation implies that
there are two times more hydrogen than oxygen. What
tube do you think was producing hydrogen? Which was
producing oxygen?
Analysis worksheets. Make sure that all ac adapters are unplugged and the water is disposed of properly.
Supplement A (ANSWERS)
Warm-Up
1. In one sentence, what does the Law of Conservation of Mass state?
Product = Reactants
Mass cannot be created nor destroyed
The law implies that mass can neither be created nor destroyed.
2. Label the chemical equation below using the following words:
Reactants
Products
Coefficients
Subscript
How many of each element are in each side of the photosynthesis equation?
6𝐶𝑂2 + 6𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2
C
H
O
#6
#12
#18
3.
SUPPLEMENT B
H2 from H2O Laboratory Procedure
Materials and Supplies:
 Amperostat electrostation
 12V AC adapters
 Tap water and sodium sulfate (Na2SO4)
 Electrode assembly, and tall 500 mL Beaker
 Clip leads (5)
Procedure:
1. Fill the tall beaker about 3/4 full with deionized or tap water, and dissolve about 20 g of Na2SO4.
2. Make sure the ON/OFF switch is set to OFF, and the dial is set to MIN. Using the included clip leads:
A) connect battery #1 (+) terminal to the Battery (+) terminal on the electrostation
B) connect Battery #2 (-) terminal to the Battery (-) on the electrostation
C) between the two batteries, connect Battery #1 (-) to Battery #2 (+) to complete the circuit.
3. Fill the electrode assembly with the solution, and then submerge the electrode assembly by inverting them quickly at 45° angle
into the beaker which is held also at 45°.
4. Again using clip leads, connect the two electrodes to the "(+) Electrode (-)" leads on the electrostation (in any order, it doesn't
matter).
5. Note the water level in each electrode test tube, and write it down in your pre-made data table.
6. Turn the electrostation ON, and adjust the dial so that the meter reads 50, 100, 150 or 200 mA (depending on your instructor's
direction).
7. Watch as gaseous bubbles evolve from the very tips of the electrodes. Run the reaction for 5-15 min as directed by your
instructor.
8. In your data table, write down the final water level in each electrode.
9. Empty the solution from the test-tube electrodes back into the beaker, and re-do the experiment under different conditions
(different time, different mA setting).
Data and Observations:
Effect of Reaction Time on H2 Production
Set to 200
mA
Time of Reaction (min)
5
Tube #1:
initial
Reading
(mLi)
Tube #1:
final
Reading
(mLf)
Gas
produced
(mLf
i)
Tube #2:
Initial
Reading
(mLi)
10
15
20
Tube #2:
Initial
Reading
(mLf)
Gas
produced
(mLf
i)
Data Analysis:
[1] In your own words, describe what happened with water during the experiment.
[2] Based on the Law of Conservation of Mass, which tube was generating H2? Which tube was
generating O2? Why?
[3] Since you know the basics of a chemical equation, write down the chemical equation that took place
in this experiment. If this equation was different from your original prediction, what was different? Why is
this version correct? If your prediction was right, explain why.