The Effect of Changing Conditions of Equilibria

Question 1

How does changing temperature affect the equilibrium constant (Kc)?

Answer 1

Changing temperature changes the value of Kc, either increasing or decreasing its value. This increase/decrease depends on whether the reaction is exo- or endothermic

Question 2

What happens to Kc if the forward reaction is exothermic and temperature increases?

Answer 2

The Kc will decrease, shifting the equilibrium to the left, favouring the backwards reaction, meaning less product is formed

Question 2

What happens to Kc if temperature decreases in an exothermic reaction?

Answer 2

Kc increases, shifting equilibrium to the right, favouring the formation more product

Question 3

What happens to Kc if the forward reaction is endothermic and temperature increases?

Answer 3

Kc increases shifting equilibrium to the right, favouring the forward reaction, meaning more products are formed

Question 3

What happens to Kc if temperature decreases in an endothermic reaction?

Answer 3

Kc decreases, shifting equilibrium t the left, favouring the formation of more reactants

Question 4

Why does a change in Kc affect the equilibrium position?

Answer 4

Kc is always in the form of products over reactants. So an increase in Kc means more products are formed and a decreases means more reactants are present

Question 5

What does the size of equilibrium constant (Kc) indicate about the equilibrium mixture?

Answer 5

The value of Kc shows whether products or reactants dominate in the equilibrium mixture

Question 6

If Kc is much greater than 1 what does it mean?

Answer 6

The equilibrium position lies to the right, meaning products dominate over reactants

Question 7

If Kc is much less than 1 what does that mean?

Answer 7

The equilibrium lies to the left, meaning reacts dominate the products

Question 8

When is reaction considered to have gone to completion based on Kc?

Answer 8

If Kc > 10 to the power of 10, the reaction is regarded to have gone to completion

Question 9

When is a reaction considered to not have taken place at all based on Kc?

Answer 9

If Kc < 10 to the power of 10, it is regarded as not occurring

Question 10

What effect do catalysts have on the equilibrium constant (Kc)?

Answer 10

Catalysts have no effect on the value of Kc, or the position of equilibrium

Question 10

Why don’t catalysts change the equilibrium position?

Answer 10

Catalysts increase the rate of both the forward and backward reactions equally, so the equilibrium position remains unchanged

Question 11

How do catalysts affect the speed of a reaction?

Answer 11

Catalysts lower the activation energy, allowing equilibrium to be reached faster