Catalysis and Activation Energy
We have seen that a catalyst increases the rate of a reaction. We explain it by considering the Fig 17.8.
In this figure Ea is the activation energy of uncatalysed reaction and E¢a is the activation energy of the catalysed reaction. A catalyst lowers the activation energy as you can see in the figure (E¢a < Ea). The reduction in activation energy is achieved by providing an alternative pathway of lower energy for the reaction.
You can also see in this figure that the relative energies of reactants and products are not changed. The enthalpy change is the same for the catalysed and uncatalysed reactions.