WHAT IS STOICHIOMETRY 1/6/12 Chapter 12 Section 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 + 3O 2  2Fe 2 O 3

Your answers should be for your reactant g/mol Your product g/mol Therefore, the law of conservation means that the mass that you begin with is the same mass you end with.

USING STOICHIOMETRY Section 12.2 Stoichiometric Calculations

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

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 C 8 H O 2  16 CO H 2 O How many moles of O 2 are needed to react fully with 4 moles of octane?

2 C 8 H O 2  16 CO H 2 O How many moles of CO 2 can form from 1 mole of octane?

2 C 8 H O 2  16 CO H 2 O 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 Fe 2 O 3 by the use of 18 moles of carbon monoxide, CO, in the following reaction? 1 Fe 2 O CO  2 Fe + 3 CO 2

How many moles of H 2 O are produced when 6 moles of O2 is consumed in burning methyl alcohol, CH 3 OH, according to the following equation? 2 CH 3 OH + 3 O 2  2 CO H 2 O