The rate of a chemical reaction is a measure of how fast the reactants are being used up and how fast the products are being made. Reactions in which a gas is produced can be used to monitor the rate.

The results recorded here show that the reaction had finished by four minutes, as no more gas was produced after that. The mean rate of reaction = 50 ÷ 4 = 12.5 cm 3 /min However, the rate decreased ...