C6.2 Rate of reaction

What 2 conditions need to be fulfilled for a chemical reaction to occur?

1. The activation energy of the chemical reaction must be overcome

2. Molecules of the reactants must undergo a collision in the correct orientation

What is collision theory?

• Collision theory states that particles must collide with sufficient energy and in the right orientation for a reation to happen

What factors affect the rate of reaction?

1. Changing concentration of a solution

2. Changing pressure of gases

3. Changing surface area of solids

4. Changing temperature

5. Use of a catalyst

6. Activation energy

What is a catalyst and what does it do?

• A substance that increases the rate of a chemical reaction without being used up or changed by the reaction.

• It decreases the activation energy of a reaction

Describe practical methods for investigating the rate of a reaction including change in mass of a reactant or product and the formation of a gas

How does changing concentration of a solution affect rate of reaction?

• Increasing concentration of particles leads to more frequent collisions between reactant particles

• Increases chances of successful collisions, therefore increasing rate of reaction

How does changing pressure of gases affect rate of reaction?

• Pressure: the force exerted on the walls of a container due to the force of gas particles colliding with the

• Increasing gas pressure means gas particles are forced into a smaller space, so they collide with the container walls more often

• This leads to more frequent collisions, increasing chances of successful collisions which leads to higher rate of reaction

How does changing surface area of solids affect rate of reaction?

• If surface area is increased, it creates more space for particles to collide

• This means particles collide more frequently, which leads to more successful collisions meaning a higher rate of reaction

How does changing temperature affect rate of reaction?

• When temperature is increased, the kinetic energy of the particles increases leading to more frequent collisions

• More frequent collisions leads to more chances of successful collisions, meaning higher rate of reaction

How does the use of catalysts affect rate of reaction?

• Catalysts are substances that speed up the rate of reaction. without being used up or changed

• With the use of a catalyst, the rate of reaction increases since catalysts help lower activation energy

• Lowering activation energy makes it easier to overcome it and have a successful reaction occur faster

How does the activation energy affect rate of reaction?

• Higher activation energy means theres a higher minimum energy to overcome

• Particles will be able to reach the minimum less often meaning they can’t collide as often

• The rate of reaction lowers