C5.3: Equilibria

Question 1

What are features of a reversible reaction?

Answer 1

Products can react to form the original reactants

Question 2

What happens when a reaction goes to completion?

Answer 2

Little or no reactants are left

Question 3

What are examples of reactions that go to completion?

Answer 3

Complete combustion of a fuel
Many precipitation reactions
Reactants where a gas product escapes

Question 4

Define dynamic equilibrium

Answer 4

When the forward and backward reaction both occur at the same rate in a reaction

Question 5

What was Le Chatilier’s principle?

Answer 5

If a system is in dynamic equilibrium, and the conditions are changed, the position of equilibrium moves to counteract the change

Question 6

What happens to the position of equlibrium in terms of concentration?

Answer 6

If the concentration of reactants is increased the foward reaction will be favoured - more products formed
If the concentration of products are increased the backward reaction will be favoured - more reactants formed

Question 7

What happens to the position of equlibrium in terms of temperature?

Answer 7

Increasing temp will favour the endothermic reaction
Decreasing temp will favour exothermic reaction

Question 8

What happens to the position of equlibrium in terms of pressure?

Answer 8

Pressure only matters if the reaction involves gas

Increasing pressure favours reaction with fewer gas moles
Decreasing presssure favours reaction that forms greater gas moles

Question 9

What would happen if there were equal moles of gas on each side?

Answer 9

Nothing due to same pressure

Question 10

How does a catalyst shift position of equilibrium?

Answer 10

Increases rate of reaction but does not affect the position of equilibrium