Lesson 8: Mole Ratios in Chemical Equations

Ratios in Chemical Equations (Molecules)

Consider the Reaction 

2H2(g) + O2(g) → 2H2O(g) + energy 

This tells us that 2 molecules of hydrogen react with one molecule of oxygen for a ratio of 2:1 (H2:O2)

This tells us that 2 molecules of hydrogen reacts to form one molecule of water for a ratio of 1:1 (H2:H2O)

This tells us that 1 molecule of oxygen reacts to form two molecules of water for a ratio of 1:2 (O2:H2O)

Mole Ratio is the ratio of the amounts of the entities in chemical reaction.

Ratios in Chemical Equations (Mols)

Consider the Reaction 

2H2(g) + O2(g) → 2H2O(g) + energy 

This tells us that 2 mol of hydrogen react with one mol of oxygen for a ratio of 2:1 (H2:O2)

This tells us that 2 mol of hydrogen reacts to form one mol of water for a ratio of 1:1 (H2:H2O)

This tells us that 1 mol of oxygen reacts to form two mol of water for a ratio of 1:2 (O2:H2O)

A freshly exposed surface of aluminum quickly reacts with oxygen to form a layer of aluminum oxide. What amount of oxygen is required to react completely with 6.4 x 10-2 mol of aluminum? 

Summary