SC12 Reversible Reactions and Equilibria

Question 1

Define reversible reactions

Answer 1

Reactions wherein the products react to reform the reactants

Question 2

Give an example of a reversible reaction

Answer 2

Ammonium chloride

Question 3

What is a reversible reaction said to achieve when it occurs in a closed container?

Answer 3

Dynamic Equilbrium

Question 4

What are the conditions that state when a reaction is at equilibrium?

Answer 4

• forward and backward reactions are still happening
• rates of forward and backward reactions are the same
• the concentration of the reactants and the products remain the same

Question 5

Define dynamic equilibrium

Answer 5

• Describing the position attained in a reversible reaction when the proportions of reactants and products stay the same.
• The term ‘dynamic’ = forward and the backward reactions continue to occur (at the same rate).

Question 6

How is ammonia manufactured?

Answer 6

Through the Haber Process

Question 7

Describe the Haber Process

Answer 7

1) Nitrogen and Hydrogen are pumped through pipes
2) A compressor increases the gas pressure to 200 atmospheres
3) The pressurised gases are heated to 450C and passed through a reaction chamber containing an iron catalyst to speed up the reaction
4) The reaction mixture is cooled so that ammonia liquefies and can be removed
5) Unreacted nitrogen and hydrogen are recycled

Question 8

What are the key conditions of the Haber process?

Answer 8

• 450C temperature
• 200 atmospheres of pressure
• iron catalyst

Question 9

What happens if you increase the temperature of the Haber process?

Answer 9

• equilibrium position shifts in the endothermic direction, which means it transfers energy from the surroundings, cooling them down

Question 10

What happens if you decrease the temperature of the Haber Process?

Answer 10

Equilibrium position shifts in the exothermic direction, heating up the surroundings

Question 11

What happens if you increase the gas pressure?

Answer 11

Equilibrium shifts in the position that forms fewer gas molecules

Question 12

What happens if you decrease the gas pressure?

Answer 12

Equilibrium shifts in the position that forms more gas molecules

Question 13

What happens if you increase the concentration of the molecules?

Answer 13

Equilibrium shifts in the direction which uses up added substance

Question 14

What happens if you decrease concentration of the molecules?

Answer 14

Equilibrium shifts in the direction that forms more of the removed substance

Question 15

What is Le Chatelier’s principle?

Answer 15

If any of the conditions of a reversible reaction are changed, the closed system will adapt to counteract whatever has been changed