At 420 K a catalyst lowers the activation energy for a reaction from 110 kJ mol−1 to 80 kJ mol−1. How does this change affect the shaded area that lies to the right of the activation-energy line on a Maxwell–Boltzmann distribution for the reacting gas?
a) The shaded area remains the same because the shape of the Maxwell–Boltzmann distribution does not change when a catalyst is added.
b) The shaded area decreases because the activation-energy line shifts to higher energy, excluding more molecules from the reacting fraction.
c) The shaded area increases because a larger portion of the distribution now lies beyond the lower activation-energy threshold.
d) The effect on the shaded area cannot be predicted without additional information about how the catalyst affects collision frequency.