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I can define stoichiometry.
I can identify the number of moles required in
a reaction based on the coefficients.
I can determine how many moles of product
will be produced based on the molar ratios
found in an equation.

Note Expectations:
 Cell phones and electronics are not in
use.
 You are taking the notes.
 You are helping the people at your table
to answer the questions.
 You are prepared to answer the
questions.
2H2 + O2  2H2O
What are the numbers in red called?
In the equation above, what is the ratio of
hydrogen atoms to oxygen atoms? How did
you figure that out?
2H2 + O2  2H2O
If you have 6 hydrogen atoms, how many
oxygen atoms do you need to react with all of
the hydrogen atoms? Why?
If you have 8 hydrogen atoms and 4 oxygen
atoms, how many water molecules would you
make? How did you figure out your answer?
 Stoichiometry is the study of
measurable relationships that exist
in chemical formulas and equations.
 It involves the relationships between
reactants and products in a chemical
reaction.
2H2 + O2  2H2O
When we talk about chemistry in the lab, are
atoms practical?
Besides atoms, what unit could the coefficients
represent?
2H2 + O2  2H2O
If you have 8 moles of hydrogen, how many
moles of oxygen do you need to react with all
of the hydrogen atoms? Why?
 Stoichiometry connects the mole
and coefficients in a balanced
equation.
 Example:
 N2H4 + 2H2O2  N2 + 4H2O
 This means that 1 mole of N2H4
reacts with 2 moles of H2O2 to
produce 1 mole of N2 and 4 moles
of H2O.
 There is now a relationship between
the coefficients and moles.
 Molar ratios allow you to determine
the number of moles of any
substance in the reaction.
 Example:
 NH4NO3  N2O + 2H2O
 How many moles of N2O and H2O
are made from 2.5 moles of
NH4NO3?
 You can convert from moles of one
substance to moles of another
substance using mole ratios.
 Example:
 Example:
4Fe + 3O2  2Fe2O3
 How many moles of Fe are needed
to react with 2.3 moles of O2?
 Balanced equations follow the law of
conservation of matter.
 The mass of the products equals the
mass of the reactants.
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What is stoichiometry?
Stoichiometry connects ____________ and
__________________.
What is a molar ratio?
How does the mass of the products in a
reaction compare to the mass of the
reactants? Why?
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I can determine a volume ratio based on
coefficients in a chemical equation.
I can determine the volume required for a
reaction or produced as a product based on
volume ratios.

Note Expectations:
 Cell phones and electronics are not in
use.
 You are taking the notes.
 You are helping the people at your table
to answer the questions.
 You are prepared to answer the
questions.

What is the volume of 1 mole of gas at STP?

Is this a constant or does it change based on
the type of gas?

If 3.8 L of H2 reacts with chlorine gas, what
volume of HCl gas will be produced?
H2 + Cl2  2HCl
 One mole of gas occupies the same
volume as any other mole of gas.
 Therefore, molar ratios in a
chemical reaction represent the
ratio of the volumes of gases.
 Volume-volume problems give you a
volume and ask you to find the
volume of an unknown.
 You will use the volume ratio from
the equation to solve these
problems.

What unit is used to measure volume?
 The volume ratio is the same as a
molar ratio, except it uses liters.

Example: N2 + 3H2 2HCl
 What volume of H2 is required to react
with 15.5 L of N2?

Example:
 If .38 L of H2 reacts with chlorine gas,
what volume of HCl gas will be
produced?
 H2 + Cl2  2HCl
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Is volume of 1 mole of gas at STP a constant
or does it fluctuate?
What is volume measured in?
What is the volume ratio?
How does the volume ratio compare to the
molar ratio?

I can determine the mass required or
produced during a chemical reaction based
on the molar ratios found in a chemical
equation.

Note Expectations:
 Cell phones and electronics are not in
use.
 You are taking the notes.
 You are helping the people at your table
to answer the questions.
 You are prepared to answer the
questions.


When we talk about moles, is mass constant
for every molecule? Why or why not?
If I give you the mass of a reactant and ask
you to fine the mass of a product, is this
possible? Why or why not?
 Since a chemical equation is related
to moles, you can now do mole
conversions using the information in
an equation.

If 20 g of H2 reacts with chlorine gas, how
many grams of HCl will be produced?
H2 + Cl2  2HCl
Talk with your table about what you think the
first step in solving this problem would be.

If 20 g of H2 reacts with chlorine gas, how
many grams of HCl will be produced?
H2 + Cl2  2HCl
Now that we have established what to do in the
first step, where are we going to go next?

If 20 g of H2 reacts with chlorine gas, how
many grams of HCl will be produced?
H2 + Cl2  2HCl
What will the final step in this problem be?
 The first step is to always convert
mass to moles, and then you can go
anywhere from there.
 The last step is to convert back to
moles of the substance you are
looking for.
 In a mass-mass problem, you are
given the mass of one substance
and asked to find the mass of
another substance in a chemical
reaction.
 Remember the coefficients are not
masses, they represent moles.

What mass of water is produced from 1.5
grams of glucose (C6H12O6)?
C6H12O6 + 6O2  6CO2 + 6H2O

When 3.8 g of Al2O3 decomposes, how many
grams of oxygen are produced?
2Al2O3  4Al + 3O2
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Is mass a constant for every molecule? Why
or why not?
In a mass-mass problem what are you looking
for?
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I can define a limiting reactant.
I can determine the limiting reactant for a
reaction based on the amount of reactants
used in a reaction.

Note Expectations:
 Cell phones and electronics are not in
use.
 You are taking the notes.
 You are helping the people at your table
to answer the questions.
 You are prepared to answer the
questions.

Can chemical reactions go on and on forever?
Why or why not?
 In chemical reactions, the amount of
product formed is dependent on the
amount of reactants available.
 The amount of gasoline in your car
limits how far you can drive.
 Predict the definition of a limiting
reactant.
 What does it mean if you have a
reactant in excess?
 Often, in a chemical reaction, there
is a reactant that limits the amount
of product that can be formed.
 A limiting reactant is one that limits
the amount of product formed in a
reaction.
 Which reactant will be used up in a
chemical reaction, the limiting
reactant or the reactant in excess?
 Which reactant will determine how
much product is made, the limiting
reactant or the reactant in excess?
Why?
 The limiting reactant will be
completely used up in the reaction.
 The other reactant or reactants will
have some left over at the end of a
reaction.
 The leftover reactant is said to be in
excess.
 The amount of product is always
determined by the limiting reactant.
 If you have 3.5g of Cu and 6.0 g of
AgNO3, which reactant is the limiting
reactant in the production of silver?
Cu + 2AgNO3  Cu(NO3)2 + 2Ag
Predict how you would solve this
problem. What are you going to look
for?
 The reactant that produces the least
amount of product is the limiting
reactant.

Identify the limiting reactant when 5.87
grams of Mg(OH)2 reacts with 12.84 grams of
HCl to produce MgCl2 and water.

We are going to break these problems into
three steps.
How much water is produced if you start with
5.87 grams of Mg(OH)2?
Mg(OH)2 + 2HCl  MgCl2 + 2H2O

How much water is produced if you start with
12.84 grams of HCl?
Mg(OH)2 + 2HCl  MgCl2 + 2H2O

Circle the limiting reactant: Mg(OH)2 or HCl.
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What is a limiting reactant?
What does it mean if a reactant is in excess?
Which reactant will determine how much
product is made, the limiting reactant or the
reactant in excess? Why?
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I can define expected yield.
I can define actual yield.
I can explain why the expected yield and
actual yield are not the same.
I can define the percent yield.
I can calculate the percent yield for a
reaction.
 The amount of product that is
produced in a reaction is usually less
than the predicted amounts.
 The amount of product that should
be produced based on calculations is
the expected yield.
 The amount of product really
obtained is the actual yield.
 Product can be lost for several
reason.
 The reactants may not react.
 The reactants may be used up in
side reactions that should not be
occurring.
 Some of the product may be lost
due to transfer between containers.
 It is useful to determine what
percent of the expected yield was
actually obtained.
 This percentage is called percent
yield.

Formula:
 % yield = actual
expected X 100

Example: A piece of copper, with a mass
of 5.00 g is placed in silver nitrate. The
silver metal produced has a mass of 15.2
g but the expected yield was 17.0 g of Ag.
What is the percent yield of silver?
 You know how to calculate the
expected yield of product based on
the calculations we have been
doing.

Example: Determine the percent yield for
the reaction between 2.8 g Al(NO3)3 and
excess NaOH if 0.966 g AL(OH)3 is
recovered.
 Al(NO3)3 + NaOH  Al(OH)3 + 3NaNO3
First calculate how much Al(OH)3 should
have been produced, then calculate the
percent yield.