Final answer:
To calculate the activation energy of the reverse reaction, subtract the reactant energy from the transition state energy. The catalyzed reaction will have a lower activation energy. The activation energies for the second steps of both mechanisms are the same.
Step-by-step explanation:
Activation energies are calculated by subtracting the reactant energy from the transition state energy.
For example, in diagram (a), the activation energy (Ea) equals 32 kJ minus 6 kJ, which equals 26 kJ.
In diagram (b), the activation energy (Ea) equals 20 kJ minus 6 kJ, which equals 14 kJ.
To identify the catalyzed reaction, compare the activation energies of both reactions. In this case, diagram (b) represents the catalyzed reaction with a lower activation energy.
The activation energies for the second steps of both mechanisms are the same, 20 kJ.