A5 Equilibrium

Question 1

Define dynamic equilibria.

Answer 1

1- Closed system.

2- Rate of the forward reaction is equal to the rate of the reverse reaction.

3- Concentrations of reactants and products do not change.

Question 2

Using Le Chatalier’s principle, explain the effect of increasing temperature.

Answer 2

1- Forwards reaction is exothermic or endothermic.

2- So increasing temperature favours the forwards or backwards reaction & equiburium shifts RHs or LHS

3- Equilibrium concentration of XXX increases.

Question 3

Using Le Chatalier’s principle, explain the effect of increasing pressure.

Answer 3

1- Fewer gas moles on the left or right.

2- Increasing pressure shifts equilibrium to the left or right hand side.

3- Equilibrium concentration of XXX increases.

4- reduces number of gaseous moles to minimise the increase in pressure

Question 4

Using Le Chatalier’s principle, explain the effect of increasing concentration of reactants

Answer 4

1- More reactant particles in mixture per unit volume.

2- Equilibrium shifts to the right hand side.

Question 5

Using Le Chatalier’s principle, explain the effect of a catalyst.

Answer 5

1- doesn’t change position of equilibrium

2- speeds up rate of forward and reverse reaction equally

3- will increase the rate at which an equilibrium is established

Question 6

In equilibria industry, what are the advantages/disadvantages of temperature?

Answer 6

High temperature = quicker rate, expensive, uses large amount of energy

Question 7

In equilibria industry, what are the advantages/disadvantages of pressure?

Answer 7

High pressure = quicker rate, expensive, dangerous.

Question 8

Why is it difficult to know the effect on equilibria if it is affected by both temperature and pressure?

Answer 8

Difficult to predict relative contributions of two opposing factors.

Question 9

Why is nitrogen accessible in industry?

Answer 9

Occurs naturally in the air.

Question 10

Explain the effect of changing temperature on the position of Kc/ kp . on left and right

Answer 10

right= Kc increases.

left = Kc decreases.

left - less

Kc NOT affected by pressure or catalysts.

Question 11

What should always be ignored in Kc calculations?

Answer 11

Solids.

Question 12

What reactants and products should only be used in Kp calculations?

Answer 12

Gases only.

Question 13

Explain the effect of increasing pressure (causing right hand shift) on the Kp equation.

Answer 13

Equilibrium shifts right, as right hand side has fewer moles.

before eqiublrim shift: Increased pressure results in denominator (side with more moles) of Kp expression increasing more than numerator.

Equibrium shift: - Numerator expression must increase to restore Kp.

Question 14

homogenous

Answer 14

contains equilbrium species that all have the same state

e.g. all gas

Question 15

heterogenous

Answer 15

contains equblrium species that have different states

Question 16

explain whether a catalytic converter acts as a homogenous or heterogeneous catalyst

Answer 16

heterogeneous

catalyss- solid - usually metal

reactants and products are gases

Question 17

Kc/ KP

Answer 17

only affected by temp

not catalysis or pressure

Question 18

KP

Answer 18

p()

p and round brackets

partial pressure

Question 19

kp/kc pressure decreases

Answer 19

Kp is the same

only affected by temp

Question 20

Answer 20

exothermic

kp decreases as temp increases

Question 21

equilibrium LHS

Answer 21

kc or kp smaller/ decreases

Question 22

equilibrium RHS

Answer 22

kc or kp greater/ increases

Question 23

catalyst key words for industry

Answer 23

reaction takes places at lower temp with lower energy demand

reduces co2 emissions/ buring fossil fuels

Question 24

Answer 24

1- kc doesn’t change with pressure

2- n2 conc increases

3- denominator increases

4- chemist is correct

5- numerators increases to restore kc

Question 25

Answer 25

N2 obtained from air H2 has to be manufactured/ doesn't occur naturally

Question 26

Answer 26

equibrium position far to the right

Question 27

Answer 27