Question

( a) For a reaction with a given Ea, how does an increase in T affect the rate?

(b) For a reaction at a given T, how does a decrease in Ea affect the rate?

Short answer

(a) (a) As the temperature rises, the fraction of molecules with energy greater than the threshold energy increases. As a result, more molecules have the activation energy to collide. As a result, the number of collisions rises, as does the rate of reaction.

(b) When the activation energy drops, more molecules have the activation energy required for collisions. As a result, the number of collisions rises, as does the rate of reaction.

Step-by-step solution

How does an increase in T affect the rate?

At any given temperature, the kinetic energy of the reactant molecules is distributed. At any given temperature, collisions between molecules have a range of energies.

The percentage of molecules with energy greater than the threshold energy grows as the temperature rises. As a result, more molecules have the activation energy needed to collide. This increases the number of collisions and, as a result, the rate of reaction.

How does a decrease affect the rate?

The kinetic energy of the reactant molecules is dispersed at every given temperature. Collisions between molecules have a variety of energies at any given temperature.

More molecules have the activation energy necessary for collisions when the activation energy decreases. This increases the number of collisions and, as a result, the rate of reaction.