Chemistry - rate of reactions

What is a chemical reaction?

Chemicals interact to form new chemicals

What is the rate of reaction?

The speed at which a chemical reaction takes place

What does collision theory say?

The speed of reaction depends on the frequency of successful/effective collisions

What does frequency mean?

Number of collsions per unit of time

What is the first thing collision theory says

Two or more reactant particles must collide

What is the second thing collision theory says

The reactants must colldie with sufficient force

What is the third thing collision theory says

They must collide with the correct orientation (correct bonds are broken or formed)

What is activation energy?

The minimum amount of energy required for a chemical reaction to proceed

What can affect the rate of reaction?

Concentration, temperature, surface area

What does concentration refer to?

The number of particles present in a given volume (e.g. mixture or solution)

How can you dilute a solution?

Adding water - increases total volume whilst the solute stays the same

How can you concentrate a solution?

Evaporating water - decreases total volume whilst solute stays the same

What does an increased concentration do?

Increases the rate of reaction as particles are more likely to collide. Leads to a high frequency of successful collisions

Why does an increased temperature increase rate of reaction?

Speeds up the reaction as there are more collisions (per second) and the collisions have more energy. This leads to a higher frequency of successful collisions.

What does the energy of particles have to do with temperature?

A higher temperature means particles get more kinetic energy. This means particles more faster and collide more frequently

What does temperature have to do with activation energy?

If temperature increases, the particles are given more energy meaning it is easier to overcome acitvation energy.

What does an increased surface area do?

Increases the amount of particles exposed to the reactant - speeds up rate of reaction

What does a catalyst do?

Increases the rate of reaction as it has a lower activation energy. This means more particles have enough energy to collide successfully.

Do catalysts get used up in a reaction?

No, they can be used again