6.2.5 - 6.2.7

6.2.5 Sketch and explain qualitatively the Maxwell-Boltzmann energy distribution curve for a fixed amount of gas at different temperatures and its consequences for changes in reaction rate.

The moving particles in a gas or liquid do not travel with the same velocity; some faster, some slower. The faster they move, the more kinetic energy they have. The distribution is shown by a Maxwell-Boltzmann curve.
This shows how activation energy distinguishes between particles that have greater or lesser values of kinetic energy. So at lower temperature (black) there are fewer particles that exceed the activation energy. When temperature rises, the curve broadens and at the same Ea (red vertical line) there will be more particles reacting as the area is bigger. The average kinetic energy is the peak of each line, which is also the mean. Change in temperature will basically change the position of the average KE.
The area under the curve shows the number of particles so it never changes. So as the temperature increases, the area under the curve does not change.

6.2.6 Describe the effect of a catalyst on a chemical reaction
A catalyst is a substance that increases the rate of reaction without itself undergoing permanent change. It never changes chemically but it could change physically. The catalyst is ‘recycled’. The catalyst brings the reactive parts of the reactant particles into close contact therefore lowers the Ea.
A catalyst provides an alternative route for the reaction which as a lower activation energy (Ea). Note that it is a completely different reaction.
As you can see, the reactants and the product remain the same but the activation energy required without a catalyst is higher.
This means that without increasing the temperature, a larger number of particles will now have kinetic energy over the Ea therefore more successful collisions.

6.2.7 Sketch and explain Maxwell-Boltzmann curves for reactions with and without catalyst.
As said earlier, a catalyst lowers the activation energy which can be shown by a leftward shift on a Maxwell-Boltzmann curve.
You can see that the area when catalyzed is bigger so this means that more particles are able to react.