Now, when you add that catalyst, what happens is that activation energy is lowered by this much to this red level. And that means more molecules, on average will have enough kinetic energy to climb this new activation barrier and form the product. And that's exactly what happens when you add a catalyst. Now, it's very important to understand the following point. Catalysts do not, and I repeat, do not affect the equilibrium of reaction. In other words, what catalysts do is they speed up their forward reaction and reverse reaction.