UNIT # 8 Introduction Objectives 8.18.2 8.3 Problems 1 | 2 | 3 | 4

CHEMICAL REACTIONS

8.5 - Calculations based on Chemical Equations

8.5.1 - Mole-mole Calculations

Given the balanced chemical equation AND the number of moles of any one of the reactants or products, the proportional number of moles of any other reactant or product can be determined by using the appropriate stoichiometric mole ratio.

In the example below, you will be given the mole of one reactant (C2H5OH) and you will be asked to find the mole of the other reactant (oxygen gas).

How many moles of oxygen gas is required to burn 3.60 moles of ethyl alcohol, C2H5OH?

Here are the steps involved to answer this question:

Step 1: Identify the chemical equation involved: a combustion reaction (review types of reactions, section 8.4)
Step 2: Write the balanced chemical equation (review balancing equations, section 8.3).
Step 3: Determine the stoichiometric ratio of the substances that you are working with specifically between ethyl alcohol and oxygen.
Step 4: Calculate the number of moles of oxygen by making the ratio specifically for 3.60 moles of ethyl alcohol.