Effect of catalysts
The rate of a reaction can be increased by adding a suitable catalyst. A catalyst is a substance which increases the rate of a chemical reaction but it is not used up (remains chemically unchanged at the end).
Only a very small amount of catalyst is needed to increase the rate of reaction between large amounts of reactants.
A catalyst is specific to a particular reaction:
- different catalysts catalyse different reactions
- not all reactions have suitable catalysts
Activation energy - Higher tier
The amount of catalyst not used up provides an alternative reaction pathway of lower The activation energy is the minimum energy required for a reaction to occur.
Activation energy is the minimum energy needed for a reaction to occur when two particles collide. It can be represented on an energy level diagram.
The diagram shows that a catalyst provided a reaction pathway of lower activation energy. This makes more of the collisions successful at a given temperature.