Equilibrium

Question 1

Reversible Reaction

Answer 1

A reversible reaction is one in which the products of the reaction react together to reform original reactants. In a reversible reaction system, one reaction direction will be endothermic and one will be exothermic. All reversible reactions reach dynamic equilibrium.

Question 2

Dynamic Equilibrium

Answer 2

This is where the rate of the forwards and backwards reaction are equal and the concentrations of reactants and products are equal. Only can happen in closed system.

Question 3

Closed System

Answer 3

A chemical system isolated from surroundings. The temp. pressure. conc. of reactants and products not affected by external influences

Question 4

Le Chatelier’s Principle

Answer 4

If a chemical system is subject to a change in conditions, the position of equilibrium will shift to lessen the effect of that change. Very useful in industrial processes. Reaction conditions are altered to get desired conditions, to maximise product yield.

Question 5

What affect does increasing the temp. have on equilibrium system?

Answer 5

1. Increasing the temp.
2. Position of equilibrium shifts towards the endothermic
   reaction
3. To get rid of excess heat
4. Increase in yield of endothermic products

Question 6

What affect does decreasing the temp. have on equilibrium system?

Answer 6

1. Decreasing temp.
2. Position of equilibrium shifts towards exothermic reaction
3. To gain heat
4. Increase in yield of exothermic products

Question 7

What affect does increasing the pressure have on equilibrium system?

Answer 7

1. Increase pressure
2. Position of equilibrium shifts towards side of reaction with fewer mol of gas
3. To release built up pressure
4. Increase product yield of reaction with fewer mol of gas

Question 8

What affect does decreasing the pressure have on equilibrium system?

Answer 8

1. Decrease pressure
2. Position of equilibrium shifts towards side of reaction with more moles of gas
3. As pressure has been lost
4. Increase product of yield of reaction with more mol of gas

Question 9

Concentration and position of equilibrium

Answer 9

Concentration of reactants is either increased or decreased and this is what impacts the position of equilibrium.

Question 10

What affect does increasing concentration of reactants have on the position of equilibrium?

Answer 10

1. Increase concentration of reactants
2. Position of equilibrium shifts towards right hand side/ favours side of reaction that produces products/forwards reaction
3. More molecules available to react
4. Increases yield of products

Question 11

What affect does decreasing concentration of reactants have on the position of equilibrium?

Answer 11

1. Decrease concentration of reactants
2. Position of equilibrium favours left hand side/backwards reaction/ shifts towards side of reaction that reforms reactants
3. Fewer molecules available to react
4. Decreases yield of products (increase in yield of reactants)

Question 12

What affect does a catalyst have on equilibrium system?

Answer 12

Catalysts have no effect on the position of equilibrium. This is because they increase the rate of the forwards and backwards reaction equally. They allow a reversible reaction to reach dynamic equilibrium faster though.4

Question 13

Kc

Answer 13

This is the equilibrium constant.

Question 14

What do the values of Kc tell us?

Answer 14

Kc = 1 : Position of equilibrium exactly half way between products and reactants
Kc > 1 : Position of equilibrium is towards the products
Kc < 1 : Position of equilibrium is towards reactants