The collision theory
The collision theory states that for a chemical reaction to occur the chemicals have to collide, they have to collide with enough energy to react and they have to collide with the correct orientation.
Factors that affect the rate of reaction.
With an increase of temperature the particles have more kinetic energy, this leads more collisions per second.
This means that the rate of reaction increases.
Temperature also changes to amount of particles that have the required activation energy to react. When heated, a greater number of the particles have the required activation energy and so there is a faster reaction rate.
A more concentrated reactant will have more particles in a given volume. This leads to more collisions per second and therefore a faster rate of reaction.
Powdered solid has a greater surface area as there is more surface exposed to collisions. This means that there are more collisions per second so a faster rate of reaction.
A catalyst lowers the activation energy needed for a reaction to take place. This means that a greater number of particles have the required energy needed to react and hence a faster rate of reaction.
A catalyst does not get used up during the reaction.