Equillibrium

Question 1

Describe what it means when the rate is at equilibrium

Answer 1

• at equilibrium, the rate of the forward and backwards reaction is the same
• the concentrations of the reactants remain constant
• equilibrium can only be achieved in a closed system at constant temperature and pressure

Question 2

What is Le Chateliers Principle?

Answer 2

When a factor is changed the equilibrium will shift to oppose the change
e.g. change in temperature or pressure

Question 3

Why is the forward reaction exothermic and the reverse reaction endothermic?

Answer 3

• exothermic : forward reaction - increases the temperature of the surroundings
• endothermic - reverse reaction - decrease the temperature of the surroundings

Question 4

Describe what would happen if we increase the temperature of the surroundings

Answer 4

• if the temperature increases
• the equilibrium will shift to the left to counteract the increase in temperature of the surroundings, therefore the reverse reaction occurs at a faster rate
• the reverse reaction is endothermic
• the yield of reactants increases

Question 5

Describe what would happen if we decrease the temperature of the surroundings

Answer 5

• If the temperature is decreased
• the equilibrium will shift to the right to counteract the decrease in temperature, therefore the forward reaction will occur at a faster rate
• the forwarded reaction is exothermic
• the yield of products increases

Question 6

Describe what would happen if we increase the pressure of the surroundings

Answer 6

• If the pressure increases
• the equilibrium will shift to the right ( as it’s the side with fewer moles) to counteract the increase in pressure, therefore the forward reaction will occur at a faster rate
• the forward reaction is exothermic
• the yield of products increases

Question 7

Describe what would happen if we decrease the pressure of the surroundings

Answer 7

• If pressure decreases
• the equilibrium will shift to the left as it is the side with fewer moles, therefore the reverse reaction will occur at a faster rate
• the reverse reaction is endothermic
• the yield of reactants increases

Question 8

Describe the effect of a catalyst on equilibrium

Answer 8

• Catalysts have no effect on the shift of equilibrium
• both forward and reverse reactions will occur at a faster rate
• equilibrium will be reached faster