Transcript Chapter 12 Section 12.1

Chapter 12
Section 12.1
WHAT IS STOICHIOMETRY
1/6/12
What is Stoichiometry
 It is the study of quantitative relationships between
amounts of reactants used and products formed by a
chemical reaction.
 For example: To help you answer the question: “
How much oxygen is required to burn a candle
completely that has a certain mass.
 This is based off of the law of conservation.
 What is the law of conservation?
 First determine the molar mass for the reactant and
product of the following:
4Fe + 3O2  2Fe2O3
 Your answers should be for your reactant 319.4
g/mol
 Your product 319.4 g/mol
 Therefore, the law of conservation means that the
mass that you begin with is the same mass you end
with.
Section 12.2
Stoichiometric Calculations
USING STOICHIOMETRY
Purpose of Stoichimetry
Ingredients
3/4 cup butter
1 1/2 cups brown sugar
2 tablespoons water
2 cups semisweet chocolate chips
2 eggs
2 1/2 cups all-purpose flour
1 1/4 teaspoons baking soda
1/2 teaspoon salt
3 (4.5 ounce) packages chocolate covered thin
mints
Makes 40 cookies
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Steps to take
 1. Balance the equation (if needed)
 2. Place values above the given and X above the
unknown
 3. Cross multiply and solve for X (the unknown)
Mole to Mole Conversion
 Your key equation here is:
Moles given x mole ratio
Example:
2 C8H18 + 25 O2  16 CO2 + 18 H2O
How many moles of O2 are needed to react
fully with 4 moles of octane?
2 C8H18 + 25 O2  16 CO2 + 18 H2O
How many moles of CO2 can form
from 1 mole of octane?
2 C8H18 + 25 O2  16 CO2 + 18 H2O
How many moles of water are
produced by the combustion of 6
moles of octane?
 How many moles of iron, Fe, can be made from Fe2O3
by the use of 18 moles of carbon monoxide, CO, in the
following reaction?
 1 Fe2O3 + 3 CO  2 Fe + 3 CO2
 How many moles of H2O are produced when 6 moles of
O2 is consumed in burning methyl alcohol, CH3OH,
according to the following equation?
2 CH3OH + 3 O2  2 CO2 + 4 H2O