Chapter 9:
Stoichiometry
Objectives:
 Write and use mole ratios from
chemical equations
 Identify limiting reagents
 Calculate percentage yields
 Distinguish theoretical and actual
yields
A. Proportionality

Perform stoichometric calculations
o Mass to mass
o Moles to mass
o Mass to moles
o Moles to moles
Chocolate chip cookie recipe
2 1/4 c. flour
1 tsp. baking soda
1 tsp. salt
1 c. butter
3/4 c. sugar
3/4 c. brown sugar
1 tsp vanilla extract
2 eggs
2 c. chocolate chips
Makes 5 dozen cookies.
If you have 5 eggs, how many cookies can be made?
B. Mole Ratios
Chemistry recipes are chemical equations
CO2
C. Using Mole
Ratios
+
2LiOH
→
Li2CO3
+
H 2O
Mole Ratios are your EQUALITIES!
2HgO
→
2Hg
+
O2
If 0.75 mole of Oxygen where produced, how many moles of mercury were
made?
D. Stoichiometry
problems
1.
2.
3.
Mole to mole
CO2 + 2LiOH → Li2CO3
+
H2O
How many moles of lithium hydroxide are required to react with 20 mol of
CO2, the average amount exhaled by a person each day?
Mole to mass
6CO2 + 6H2O → C6H12O6 + 6O2
How many grams of glucose is made if 3 moles of water react?
Mass to moles
6CO2 + 6H2O → C6H12O6 + 6O2
How many moles of water are needed to react with 132 g of carbon dioxide?
Mass to mass
Sn
+
2HF →
SnF2
+ H2
If you start with 30 g of HF, how many grams of SnF2 can you make?
E. Limiting and
Excess reactants
Limiting Reactant
Excess Reactant
1.
2.
3.
79 g of zinc react with 81 g of HCl. Identify the limiting and excess
reactants. How many grams of ZnCl2 are made?
Zn
F. Percent Yield
+
2 HCl
→
ZnCl2
+
H2
What’s the percent yield if you collected 3.6 g
of a compound and the stoichiometric
amount is 4.5g?
% yield 
actual yield
x100
theoretical yield