How do catalysts affect rates of reaction?
A catalyst increases the reaction without chemically changing the substances involved.
When you make Kool-aid, you could pour the powder into the water and then walk away and wait 20 or thirty minutes for the Kool-aid to diffuse evenly throughout the water. However, most of us are impatient and we like to stir things up. By string with a spoon, the spoon acts as catalyst and increases the rate at which the Kool-Aid diffuses. But the spoon does not change the characteristics of the Kool-Aid
I hope this was helpful.