Reversible Reactions and Equilibrium (TOPIC 19)

Question 1

Describe the thermal decomposition of Ammonium chloride

Answer 1

Ammonium chloride is a white solid.

When heated in breaks down into the gases ammonia and Hydrogen chloride - Forwards reaction.

When cooled down the ammonia and the hydrogen chloride reform into ammonium chloride solid - Reverse reaction.

Question 1

What is a Reversible Reaction?

Answer 1

A reaction that can go in both the forwards and the reverse directions

Question 2

What is Dynamic Equilibrium?

Answer 2

When a reversible reaction occurs in a closed system then a state of equilibrium will be reached where the rate of the forward reaction is equal to the rate of the backwards reaction.

The concentration of reactants and products will remain constant (given that there is no change to external conditions eg. Temperature or pressure)

Question 3

What would happen to the position of equilibrium if you increased the temperature of the system?

Answer 3

The position of equilibrium would shift in the endothermic direction to use up the extra heat

Question 4

What would happen to the position of equilibrium if you decreased the temperature of the system?

Answer 4

The position of equilibrium will shift in the exothermic direction to produce more heat

Question 5

What would happen to the position of equilibrium if you increased the pressure of the system?

Answer 5

The position of equilibrium will shift to the side with the least number of molecules to encourage the reaction that produces fewer moles of gas

Question 6

What would happen to the position of equilibrium if you decreased the pressure of the system?

Answer 6

The position of equilibrium will shift to the side with the highest number of molecules

Question 7

Why does adding a catalyst have no effect on the position of equilibrium in a closed system?

Answer 7

As it increases the rate of reaction in both the forwards and the reverse direction at the same speed. Therefore there is no change.