P1C12 - Reversible reaction + equilibrium

Question 1

What is a reversible reaction?

Answer 1

chemical reactions that can proceed in both forwards and backwards directions

Question 2

What if the forward reaction is exothermic?

Answer 2

The backwards reaction will be endothermic.

Question 3

What does an exothermic reaction do in a reaction?

Answer 3

(Transfers energy from reactants to the environment)

Question 4

What does an endothermic reaction do in a reaction?

Answer 4

(transfers energy from the environment to the reactants).

Question 5

Why is the making of ammonia in the Haber process an example of a reversible reaction?

Answer 5

The formation of ammonia during the Haber process is a reversible reaction between nitrogen and hydrogen

Question 6

How can the he energy transfers that take place in exothermic and endothermic reactions be measured?

Answer 6

By monitoring the temperature of the surroundings.

Question 7

What is a closed system?

Answer 7

A system where reactants and products can neither be added nor removed.

Question 8

What happens in dynamic equilibrium

Answer 8

• The rates of the forwards and backwards reactions are equal.

The concentrations of reactants and products do not change when a reaction is at dynamic equilibrium.

Question 9

Why is dynamic equilibrium ‘dynamic’?

Answer 9

The equilibrium is dynamic because both the forward and backward reactions are still taking place.

Question 10

What does Le Chateliers principle state?

Answer 10

Says that if any of the conditions of a reversible reaction at equilibrium are changed, the closed system will adapt to counteract whatever has changed

Question 11

What is Le Chateliers principle used for?

Answer 11

This principle is used to predict the outcome of changes imposed on a system at equilibrium.

Question 12

What does changing the conditions in a reversible reaction do?

Answer 12

It may affect the position of equilibrium.

Question 13

What happens if you increase the temperature in an equilibrium reaction?

Answer 13

The position of equilibrium will shift in the endothermic direction.

The amount of products generated by the endothermic reaction will increase.
The amount of products generated by the exothermic reaction will decrease.

Question 14

What happens if you decrease the temperature in an equilibrium reaction?

Answer 14

The position of equilibrium will shift in the exothermic direction.

The amount of products generated by the endothermic reaction will decrease.
The amount of products generated by the exothermic reaction will increase.

Question 15

What happens if you increase the pressure in an equilibrium reaction?

Answer 15

The position of equilibrium will shift to favour the reaction that produces the fewest gas molecules.

Question 16

What happens if you decrease the pressure in an equilibrium reaction?

Answer 16

The position of equilibrium will shift towards the side of the reaction that produces the most gas molecules.

Question 17

How can you predict the outcome of a pressure change?

Answer 17

Assess balanced equations to see how many gas molecules are on each side of the equation.

Question 18

What happens if you increase the concentration in an equilibrium reactant?

Answer 18

Increasing reactant concentration favours the forward reaction.

This will shift the position of equilibrium towards the products.

Question 19

What happens if you decrease the concentration in an equilibrium reactant?

Answer 19

Increasing product concentration favours the backwards reaction.

This will shift the position of the equilibrium towards the reactants.