Chemistry 9701/13 — May/June 2015

The diagram shows the Boltzmann energy distribution curve for molecules of a mixture of two gases at a given temperature. For a reaction to occur the molecules must collide together with sufficient energy.

$E_a$ is used to represent the activation energy for the reaction between the gases. Of the two values shown, one is the activation energy for a catalysed reaction, the other for an uncatalysed reaction.

Which statement about $E_{a1}$ is correct?

Options

A   $E_{a1}$ corresponds to a catalysed reaction with fewer effective collisions than the uncatalysed reaction.
B   $E_{a1}$ corresponds to an uncatalysed reaction with fewer effective collisions than the catalysed reaction.
C   $E_{a1}$ corresponds to a catalysed reaction with a greater number of effective collisions than the uncatalysed reaction.
D   $E_{a1}$ corresponds to an uncatalysed reaction with a greater number of effective collisions than the catalysed reaction.