Factors affecting the rate

You will be expected to remember the factors that affect the rate of reactions, and to plot or interpret graphs from rate experiments.

How to increase the rate of a reaction

The rate of a reaction increases if:

• The temperature is increased
• The concentration of a dissolved reactant is increased
• The pressure of a reacting gas is increased
• Solid reactants are broken into smaller pieces
• A catalyst is used

Rate of reaction and changing conditions

The graph above summarises the differences in the rate of reaction at different temperatures, concentrations and size of pieces. The steeper the line, the greater the rate of reaction. Reactions are usually fastest at the beginning, when the concentration of reactants is greatest. When the line becomes horizontal, the reaction has stopped.