C8

Question 1

what is activation energy?

Answer 1

the minimum amount of energy that particles must have to react

Question 2

increase the likelihood of particles reacting by

Answer 2

increasing the frequency of their collisions,
increasing the energy they have when they collide

Question 3

how does increase SA:V ratio affect rate of reaction?

Answer 3

more particles exposed and able to react at a time
so increased rate of reaction

Question 4

which affects the rate of reaction more: the frequency of particle collisions or the energy particles have while colliding

Answer 4

the energy: how much more than activation energy they have

Question 5

how does increasing concentration affect rate of reaction

Answer 5

more reactants in a given volume
so they are closer together
so they have more successful energetic collisions

Question 6

how do catalysts increase rate of reaction

Answer 6

lower the activation energy needed for particles to react
so more particles have sufficient energy to react
so more successfully and energetically collide

Question 7

advantages and disadvantages of catalysts

Answer 7

• increase rate of reaction more cheaply than increasing temperature or pressure,
• an alternative to burning fossil fuels, so helps the environment by reducing greenhouse gas emissions,
• is not fully used up in a reaction so can be reused,
• eventually a catalyst becomes ‘poisoned’ so can no longer be reused.

Question 8

what does it mean for a reversible reaction to be in equilibrium?

Answer 8

the rate of the forward reaction is equal to that of the reverse reaction

Question 9

describe Le Chatélier’s Principle

Answer 9

when a change in conditions is introduced to a reaction in equilibrium

the position of equilibrium shifts to counter the change