1.6 Chemical equillibria

Question 1

What is dynamic equillibria

Answer 1

A dynamic equillibria exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations do not change

Question 2

Describe the reactions in dynamic equillibria

Answer 2

• The forward reaction starts off fast but becomes slow as the reactants become less concentrated
• The reverse reaction starts as nothing, but then gets faster as the products build up
• If temp. stays constant, the reactions will become equal and opposite - reaching equillibrium

Question 3

State Le Chateliers principle

Answer 3

When a change is applied to a closed system, the equillibrium will shift to oppose the change

Question 4

Explain increasing temp on a dynamic equillibium

Answer 4

Increasing temp
Favours the endothermic reaction
Because the system wants to absorb the heat that it was initially given, opposing its effect

Question 5

Explain decreasing temp on a dynamic equillibium

Answer 5

Decreasing temp
Will favour the exothermic side
Because it will want to oppose the it and let off more heat

Question 6

Explain increasing pressure on a dynamic equillibium

Answer 6

Increasing pressure
system wants to oppose the change
favours the side with fewer moles
because this will help release the pressure

Question 7

Explain decreasing pressure on a dynamic equillibium

Answer 7

Decreasing the pressure
system will oppose the change
favours the side with more moles
as pressure has been lost and it needs to make it up

Question 8

Explain increasing concentration on a dynamic equillibium

Answer 8

Increasing concentration
favours the reaction that produces the products (forward reaction)
as more moelcules are available to react

Question 9

Explain decreasing concentration on a dynamic equillibium

Answer 9

Decreasing concentration
favours the reaction that reforms the reactants
Backwards reaction, because it weants to make up for its loss in conc.

Question 10

Explain adding a catalyst on a dynamic equillibium

Answer 10

Does not change the equillibrium, just makes it easier and quicker to reach

Question 11

How do you work out the equillibium constant (Kc)

Answer 11

conc. products / conc. reactants

any moles are raised to the power of

Question 12

What affects / doesnt affect equillibrium constant

Answer 12

Not affected by - catalyst, conc.
Affected by - temperature