How does a catalyst and increasing temperature affect the rate of reaction?

For a reaction to occur between particles (reactants) they must overcome an energy barrier. This is called the activation energy. A catalyst provides an alternative pathway for the reaction, that has a lower activation energy. This means there are now more particles with the activation energy and so the rate will increase.  Increasing the temperature has no effect on the activation energy. The temperature changes the amount of energy the particles have. Increasing the temperature will mean there are more particles with high energy, greater than the activation energy, so a higher chance of a successful reaction. This means that an increase in temperature will increase the rate.  Boltzmann distribution diagrams can be used to visualise these concepts as they show the number of particles with a certain amount of energy. The area under the curve where energy is greater than the activation energy shows the number of particles that can react to give a product. Adding a catalyst or increasing the temperature will increase the number of particles in this area and so indicates the rate will increase.