Effect of Concentration and Pressure on Rate

In this lesson you will learn how changing the concentration of a solution or the pressure of a gas affects the rate of a chemical reaction. You will also study the core practical investigation for this topic and learn how to interpret the graphs produced. These concepts are tested regularly in the Edexcel GCSE Chemistry (1CH0) exams.

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Effect of Concentration on Rate

When the concentration of a reactant in solution is increased, there are more particles of that reactant in a given volume. This leads to:

1. More frequent collisions between the reactant particles.
2. Therefore more successful collisions per second.
3. So the rate of reaction increases.

The total amount of product formed remains the same (provided the same total amount of reactant is used), but it is produced more quickly.

Concentration	Number of particles in a given volume	Collision frequency	Rate of reaction
Low	Fewer particles	Less frequent collisions	Slower
High	More particles	More frequent collisions	Faster