Controlling Reaction Rates
Five key factors control how fast chemical reactions happen: catalyst, concentration, particle size, pressure, and temperature. These factors all work by affecting how particles collide with each other.
Collision theory explains that particles must crash into each other to react. However, not every collision leads to a reaction - particles need enough energy to overcome the activation energy (EA), which is the minimum energy barrier that must be crossed.
For successful collisions, you need two things: particles with kinetic energy greater than the activation energy (EK > EA), and the correct collision geometry where particles hit each other at the right angle.
Key Point: Think of activation energy like a hill - particles need enough speed to get over it before they can react on the other side.