Exam Style Question - 3

Question: Explain how a catalyst increases the rate of a reaction. Refer to the Maxwell-Boltzmann distribution in your answer. (3 marks)A catalyst provides an alternative reaction pathway with a lower activation energy. The catalyst is not used up and is chemically unchanged at the end of the reaction.On a Maxwell-Boltzmann distribution the curve itself does not change, because the temperature is the same. A new, lower activation energy is marked to the left of the original E_a.A greater proportion of molecules now have energy greater than or equal to the lower activation energy, shown by the larger area under the curve beyond the new E_a. So more collisions are successful per unit time and the rate increases.A common mistake is to say that a catalyst gives the molecules more energy or shifts the curve. It does neither: the distribution stays the same and only the energy barrier is lowered.