WHAT IS STOICHIOMETRY1/6/12

Chapter 12Section 12.1

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/molTherefore, the law of conservation means

that the mass that you begin with is the same mass you end with.

USING STOICHIOMETRY

Section 12.2Stoichiometric Calculations

Purpose of Stoichimetry

Ingredients3/4 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

mintsMakes 40 cookies

Steps to take

1. Balance the equation (if needed)2. Place values above the given and X above

the unknown3. Cross multiply and solve for X (the

unknown)

Mole to Mole Conversion

Your key equation here is:Moles given x mole ratioExample:                    

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