Kinetics I

Question 1

How does concentration affect the rate of reaction?

Answer 1

• An increase in concentration results in more particles in a given volume
• This results in an increase in collision frequency
• Consequently there is an increase in rate

Question 2

How does pressure affect the rate of reaction?

Answer 2

• Higher pressure compress a gas
• Which effectively increases its concentration as there are more particles in a given volume
• This increases the frequency of collisions and therefore there’s an increase in rate

Question 3

How does pressure affect the rate of reaction?

Answer 3

• Higher pressure compress a gas
• Which effectively increases its concentration as there are more particles in a given volume
• This increases the frequency of collisions and therefore there’s an increase in rate

Question 4

How does surface area affect the rate of reaction?

Answer 4

• Subdividng a large piece of solid into smaller parts increases the total surface area
• So more particles are exposed resulting in a higher probability of collisions between reactants
• Consequently there’s an increase in rate

Question 5

How does temperature affect the rate of reaction?

Answer 5

• An increase in temperature increases the average kinetic energy of the particles
• This results in an increase in collision frequency
• A greater number of particles have E => Ea
• Consequently there’s an increase in successful collisions and therefore an increase in rate

Question 6

How do catalysts affect the rate of reaction?

Answer 6

Catalysts work by providing an alternative reaction pathway with a lower activation energy
- Greater number of particles will have E => Ea
- Consequently there’s an increase in the number of successful collisions and therefore an increase in rate

Question 7

How do you calculate rate?

Answer 7

Rate of reaction = amount of reactant used or amount of product formed/time taken

Question 8

How do you find the rate of change of concentration?

Answer 8

Slope or gradient

Question 9

What does the Maxwell-Boltzmann distribution show?

Answer 9

Shows how the average kinetic energy is distributed among the particles at a given temperature

Question 10

What happens to the distribution curve at higher temperatures?

Answer 10

At higher temperature, the average KE of the particles increases. The distribution curve shifts to the right and becomes broader. The area under the curve should be the same as it represents the number of particles in the sample. As shown by the shading, at a higher temperature, more particles have E => Ea so a greater proportion of the collisions will be successful

Question 11

Can we use the Maxwell-Boltzmann distribution curve to explain what happens if a catalyst is added to the reaction mixture?

Answer 11

A catalyst provides an alternative route with a lower activation energy. When choosing where to add the new Ea make sure it’s still to the right of the hump. The shading shows that more particles have E => Ea when the reaction is catalysed, so a greater proportion of the collisions will be successful