What is Stoichiometry?

Stoichiometry is the ratio of moles of all reactants and products involved in a chemical reaction. It shows the relative quantities of the reactants that will be required for a given reaction and those of the products that will be formed from the reaction.

The stoichiometry of a chemical reaction can be determined from the balanced equation for the reaction. For example, the stoichiometry of the reaction between nitrogen and hydrogen to produce ammonia can be deduced from the balanced equation:

N2 + 3H2 → 2NH3

From the balanced equation above, the stoichiometry is given as 1:3:2. This means that one mole of nitrogen is needed to react with three moles of hydrogen to produce two moles of ammonia.

Uses of Stoichiometry

Stoichiometry is used to determine the right quantity of reactants to be used in any chemical experiment or project so that wastage of materials is avoided. Without being guided by stoichiometry it could also be dangerous to have certain reactants in excess quantities in the reaction system.

Stoichiometry enables chemists to calculate or predict the quantity of products that will be formed in terms of moles, mass, and volume. It also makes it possible for them to determine or predict the quantity of reactants that will be used up in the reaction, and the percentage used or unused.