Chemistry CCEA AS Level 2.9 (Kinetics)

What must happen for a reaction to occur according to simple collision theory?

The particles must collide with each other/the collision must have enough energy to overcome the activation energy barrier/The particles must collide in the correct orientation

What is activation energy?

the minimum amount of energy required for a reaction to occur

What is reaction rate?

The change in concentration of a reactant or product with respect to time

What are the units of reaction rate?

mol dm-3s-1

Why is rate of reaction fastest at the start of a reaction?

There are more reactant particles and therefore more frequent collisions

How does concentration affect the rate of reaction?

The higher the concentration the faster the rate of reaction

Why does concentration affect rate of reaction?

In a higher concentration there are more particles per unit volume and therefore there is a greater chance of collision

How does pressure affect the rate of reaction?

The higher the pressure the faster the rate of reaction

Why does pressure affect rate of reaction?

At a higher pressure there are more particles in a fixed volume and therefore a greater chance of collision

How does temperature affect the rate of reaction?

The higher the temperature the faster the rate of reaction

Why does temperature affect the rate of reaction?

At higher temperature the molecules have more energy and will therefore move faster and collide more frequently and more molecules will have energy higher than the activation energy meaning there will be more successful collisions

Why do catalysts affect the rate of reaction?

Catalysts lower the activation energy barrier so that more of the particles have energy greater than the activation energy and there will be more successful collisions

What is a catalyst?

A substance which increases the rate of a chemical reaction but does not get used up