91Ó°ÊÓ

Catalyst are substances which increases the rate of the reaction without getting used up by themselves while decreasing the activation energy of the reaction. Activation energy is the energy difference between the initial reagents and the transition state(it is the state where the energy is maximum on the reaction coordinate diagram).

• Catalyst increases the rate of reaction.
• Catalyst accelerates the rate of a reaction by decreasing the activation energy.
• Catalyst is regenerated during the reaction.

Therefore, reaction (a) has higher activation energy compared to reaction (b). Hence, reaction (a) with higher activation energy has the slowest rate and reaction (b) with lower activation energy has the highest rate. Thus, reaction (a) has slowest rate and reaction (b) has the highest rate.