1.5 Kinetics

Question 1

What must particles do in order to react?

Answer 1

• collide with sufficient energy (activation energy) and the correct orientation

Question 2

Do most collision result in a reaction?

Answer 2

• No

Question 3

Define activation energy.

Answer 3

• the minimum energy that particles must collide with for a reaction to occur

Question 4

Draw a labelled Maxwell-Boltzman curve. Label the average energy, activation energy and most probable energy. Draw in a different colour the effect of increasing temperature.

Answer 4

Question 5

What is the effect of increasing temperature on rate of reaction? Why?

Answer 5

• increasing temperature → increased rate of reaction
• much higher proportion of particles have energy greater than the activation energy.
• more successful collisions per seconds
  ∴ increased rate

Question 6

What is the effect of increasing concentration/pressure on rate of reaction? Why?

Answer 6

• increased concentration/pressure → increased rate of reaction
• because there are more particles in a given volume meaning more frequent collision
  ∴ increased rate

Question 7

What is a catalyst?

Answer 7

• a substance which increases the rate of reaction but it not used up in the reaction

Question 8

How do catalyst work and how do they increase the rate of reaction?

Answer 8

• provide an alternative reaction pathway (one with a lower activation energy)
• lowers activation energy, so more particles have energy > activation energy
• therefore more frequent successful collisions, so increased reaction rate