Equilibria

Question 1

What is Le Chatelier’s Principle? (3)

Give the full definition and what it is used for.

Answer 1

• Le Chatelier’s principle states that if a chemical system at equilibrium is subjected to a change in concentration, pressure or temperature, the position of equilibrium will shift to counteract the change.
• The principle is used to predict the effect of physical changes on equilibrium.

Question 2

What does the ‘position’ of an Equilibrium Mean? (2)

Answer 2

• If the position is to the left, more reactants are formed.
• If the position is to the right, more products are formed.

Question 3

How does changing Concentrations Affect Equilibrium Position?

Answer 3

• An increase in the concentration of reactants - this shifts the equilibrium position to the right, using up more reactants.
• An increase in the concentration of products - this shifts the equilibrium position to the left, using up more products.

Question 4

How does Adding a Catalyst affect Equilibrium Position?

Question 5

What is dynamic equilibrium?

Answer 5

State in a closed system where forward and reverse reactions occur at equal rates, so concentrations remain constant.

Question 6

What happens to concentrations at equilibrium?

Answer 6

They remain constant (not equal).

Question 7

What does Le Chatelier’s principle state?

Answer 7

A system responds to oppose changes imposed on it.

Question 8

Effect of increasing concentration?

Answer 8

Equilibrium shifts to reduce the added substance.

Question 9

Effect of increasing pressure (gases)?

Answer 9

goes to less molecule side

Question 10

Effect of temperature increase?

Answer 10

Shifts in endothermic direction

Question 11

Why does a catalyst not affect equilibrium position?

Answer 11

shifts both the same faster much

Question 12

Why must equilibrium be closed?

Answer 12

Prevents loss of reactants/products so equilibrium can establish

Question 13

What happens to rate at equilibrium?

Answer 13

Forward rate = reverse rate.