Chemistry R2.2

What is activation energy

The minimum amount of energy required to start a chemical reaction

What is the rate of reaction

The speed at which a reaction occurs (formation of product or using up of reaction over a certain period of time)

Change in concentration/change in time

What is collision theory

In order for a reaction to occur, particles must collide successfully, this includes:

1) Must have sufficient energy to collide (be at or exceed Ea - activation energy)

2) Must collide at the correct geometry/angle

How does concentration affect RoR

Higher concentration increases RoR because of collision theory. There are more particles enclosed within the same amount of space, so they’re closer together. This results in more collisions between particles, thus more successful collisions, thus reaction occuring quicker.

How does temperature affect RoR

Temp gives particles more kinetic energy (they’re moving faster) so more particles will be at/exceeding the activation energy. Also, moving faster means more collisions = more successful collisions = reaction speeds up.

How does a catalyst affect RoR

Catalysts lower the activation energy of the reaction, so more particles will have exceeded the minimum amount of energy required to collide successfully with other particles. More successful collisions = faster rate of reaction. It provides an alternative pathway for the reaction to occur.

How does pressure affect RoR

This is only in gasses. Pressure results in more particles being closer together since the space they have to move is smaller. Thus, they will collide more, leading to more successful conditions and so a faster RoR

How does surface area affect RoR

The increase in surface area leads to more particles being exposed to surrounding reactants so more collisions will occur = more successful collisions = faster RoR