BRAINCAKEEffect of Pressure
For reactions involving gases, increasing the pressure increases the rate of reaction.
Pressure is usually increased by reducing the volume of the container at constant temperature. The same number of gas molecules is then packed into a smaller volume, so there are more molecules per unit volume. Increasing the pressure of a gas is therefore the same as increasing its concentration.
With the molecules closer together, they collide more frequently, so there are more successful collisions per unit time and the rate increases. As with concentration, the energy of the molecules does not change, so the proportion of collisions with energy greater than or equal to the activation energy stays the same.
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Key terms in this lesson
- activation energy
- The minimum energy that colliding particles must have for a reaction to occur.
More in Reaction Rates
- Collision Theory
- Activation Energy
- Steric Hindrance
- Effect of Concentration
- Effect of Surface Area
- Maxwell-Boltzmann Distribution Curve
- Effect of Temperature
- Collisions in Solution
All 12 lessons in Reaction Rates · All Edexcel AS-level Chemistry topics