1. Chapter 9- Stoichiometry:
The mass relationships between reactants and products
in a chemical reaction.
I have a yellow hat on!
Stoichiometry is like following a recipe
Focuses on mass or molar relationships
Key is a balanced equation and reading the equation in terms of…Coefficients

2. Let’s try this: Na + Cl2 Type of reaction? Balanced equation
How is this read in terms of moles?
What are all the possible mole ratios?
“RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass

3. Let’s try this: Na + Cl2 NaCl Type of reaction? Balanced equation
How is this read in terms of moles?
What are all the possible mole ratios?
“RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass

4. Let’s try this: Na + Cl2 NaCl Type of reaction? Combination
Balanced equation
How is this read in terms of moles?
What are all the possible mole ratios?
“RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass

5. Let’s try this: 2Na + Cl2 2NaCl Type of reaction? Combination
Balanced equation
How is this read in terms of moles?
What are all the possible mole ratios?
“RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass

6. Let’s try this: 2Na + Cl2 2NaCl Type of reaction? Combination
Balanced equation
How is this read in terms of moles?
2 moles of Na react with 1 mole of Cl2
to produce 2 moles of NaCl

7. Let’s try this: 2Na + Cl2 2NaCl What are all the possible mole ratios?
2 mol Na 2 mol Na 1 mol Cl2
1 mol Cl2 2 mol NaCl 2 mol NaCl
2 mol NaCl 2 Mol NaCl 1 mol Cl2
2 mol Na 1 mol Cl mol Na

8. Let’s try this: 2Na + Cl2 2NaCl
5. “RECIPE” for moles to moles, moles to mass, mass to moles and mass to mass
Remember that you cannot use a mass-mass
ratio. You must convert to mol first and then
back into grams.

9. Conversions of Quantities in Moles
CO2 + 2LiOH → Li2CO3 + H2O
How many moles of lithium hydroxide are
required to react with 20 moles of carbon
dioxide, the average amount exhaled by a
person each day?

10. Conversions of Quantities in Moles
CO2 + 2LiOH → Li2CO3 + H2O

11. Conversions of Quantities in Moles
CO2 + 2LiOH → Li2CO3 + H2O
2 mol LiOH
1 mol CO2

12. Conversions of Quantities in Moles
CO2 + 2LiOH → Li2CO3 + H2O
2 mol LiOH x mol LiOH
1 mol CO mol CO2 X

13. Conversions of Quantities in Moles
CO2 + 2LiOH → Li2CO3 + H2O
2 mol LiOH x mol LiOH
1 mol CO mol CO2
x mol LiOH X =

14. Let’s pretend we have 7,000,000 hot dogs
Limiting Reagent
Let’s pretend we have 7,000,000 hot dogs
But only 600 hot dog buns
X 1,000,000
X 100

15. Q- How many hot dogs can you make?
Limiting Reagent
Q- How many hot dogs can you make?

16. Q- How many hot dogs can you make?
Limiting Reagent
Q- How many hot dogs can you make?
A – Only 600

17. Limiting Reagent Once a reactant is used up, there can
be no more products produced
(The substance that is used up first is called the)
limiting reagent =
the reactant that limits the amount of the other
reactant that can be combined and thus the
product that is produced
Excess reagent =
the substance not used up completely

18. Let’s try a problem: HCl + NaOH NaCl + H2O 2 mol 2.5 mol
Determine the limiting reagent for this reaction.
(This is done by comparing the 2 given value in
a ratio.)

19. Pick one of the givens and solve:
Let’s try a problem:
HCl + NaOH NaCl + H2O
2 mol mol
Pick one of the givens and solve:
1 mol HCl x mol HCl
1 mol NaOH mol NaOH
x mol HCl = =

20. Let’s try a problem: HCl + NaOH NaCl + H2O 2 mol 2.5 mol
2.5 mol HCl: But what does this mean?
This means that in order to react ALL
2.5 mol NaOH, you would need AT LEAST
2.5 mol HCL.
But you only have 2 mol HCl, so it LIMITS
the reaction. Hence: limiting reagent.

21. Percentage Yield
Theoretical yield = what you calculate or expect under perfect conditions
Actual Yield = what you get in the lab
Percentage Yield = x 100%
Actual Yield
Theoretical Yield