# Rates and temperature

The greater the rate or frequency of , the greater the rate of reaction. If the of the reaction mixture is increased:

• move more quickly
• the of the particles increases
• the frequency of successful collisions between reactant particles increases
• the proportion of collisions which are successful also increases
• the rate of reaction increases
Question

Explain what is meant by a ‘successful’ collision.

A collision between reactant particles with enough energy, eg the activation energy or more, to produce a reaction.

### Graphs

The rates of two or more reactions can be compared using a graph of or of formed against time. The graph shows this for two reactions.

Comparing reactions of different temperatures

The of the line is equal to the rate of reaction. The faster reaction at the higher temperature:

• gives a steeper line
• finishes sooner
The effect of temperature on the rate of reaction is due to two factors: frequency of collisions and energy of collisions. The increase in energy is usually the more important factor.