Mole Ratios

Stoichiometry The method you use to figure out how much of a chemical you can make, or how much you need, during a reaction. To do this, we need to use a mole ratio to estimate how much we are going to get based on the amount we put in.

Balance the chemical equation! To Use a Mole Ratio: Balance the chemical equation! Remember: the coefficient in a balanced equation represents the relative amounts in moles of the reactants and products. Ex: CH4 + O2  CO2 + H2O CH4: O2: CO2: H2O:

Identify the mole ratios you have. A mole ratio is a conversion factor that relates the amounts in moles of any two substances involved in a reaction. Ex: CH4 + O2  CO2 + H2O

Use the mole ratio to calculate the moles produced from the given amount. Start with what you are given. Draw the Train Tracks. Write the mole ratio next! Remember, the unit you start with needs to go on the bottom to cancel out. Do the math and write your units.

Examples: How many moles of O2 are needed to react with 21 moles of H2O? How many moles of Al2O3 are produced with 15 moles of Al are reacted? How many moles of Fe2O3 are required to produce 9 moles of Fe?