Chapter 6: Equilibrium

Question 1

State Le Chatelier’s Principle.

Answer 1

When a change is made to a system in equilibrium, the equilibrium position shifts to oppose the change.

Question 2

Features of a dynamic equilibrium:

Answer 2

(Closed system) The rates of the forward and back reactions are equal The concentrations of reactants ad products do not change.

Question 3

Write a K_c expression for

A + 2B = C + D

Answer 3

K_c = [C][D] / [A][B]²

Units are MxM / MxM²

which simplifies to M^-1, or mol^-1dm³

Question 4

Effect of decreasing temperature on an endothermic equilibrium

Answer 4

K_c will go down and equilibrium shifts left

Reverse reaction is exothermic; reducing temperature favours exothermic direction as this opposes the change made by cooling the system

Question 5

Effect of increasing temperature on endothermic equilibrium

Answer 5

Kc will go up and equilibrium shifts right

Forward reaction is endothermic; increasing temperature favours endothermic direction as this opposes the change made by heating the system