Le Chatelier's Principle

Question 1

What are the three factors that can affect the position of equilibrium in a reversible reaction?

Answer 1

• Temperature
• Pressure
• Concentration

Question 2

What does Le Chatelier’s principle state?

Answer 2

If there’s a change in concentration, pressure or temperature in a reversible reaction, the equilibrium position will move to help counteract that change

Question 3

All reactions are exothermic in one direction and endothermic in the other.

Explain how the position of equilibrium is affected by changing the temperature of a reversible reaction.

Answer 3

• Decreasing the temperature causes the equilibrium to move in the exothermic direction to produce more heat
• Increasing the temperature causes the equilibrium to move in the endothermic direction to absorb more heat

Question 4

Explain how the position of equilibrium is affected by changing the pressure applied to a reversible reaction.

(changing this only affects equilibria involving gases)

Answer 4

• Increasing the pressure causes the equilibrium to move towards the side that has fewer moles of gas to reduce pressure
• Decreasing the pressure causes the equilibrium to move towards the side that has more moles of gas to increase pressure

Question 5

Explain how the position of equilibrium is affected by changing the concentration of the reactants or products in a reversible reaction.

Answer 5

• Increasing the concentration of the reactants causes the equilibrium to move to the right to use up the reactants, making more products
• Increasing the concentration of the products causes the equilibrium to move to the left to use up the products, making more reactants

(decreasing the concentration has the opposite effect)

Question 6

(Exam-style question)

Answer 6

Question 7

(Exam-style question)

Answer 7