6.3 Equilibrium reactions in industry

Question 1

What method is used to make ammonia made in industry

Answer 1

. React nitrogen and hydrogen together in a reversible reaction which is exothermic forward.

. This happens in the HABER process

. The nitrogen and hydrogen are fed into a converter, and an iron catalyst is used

Question 2

Where does the nitrogen and hydrogen come from for the reaction to make ammonia

Answer 2

Nitrogen comes from air

Hydrogen comes from the natural gas methane in the reaction:
CH4 + H2O –> CO + 3H2

Question 3

What is ammonia used for

Answer 3

Fertilisers eg ammonium nitrate, ammonium sulfate and urea

Some can also make plastics, explosives and synthetic fibres eg nylon

Question 4

What are the ideal conditions for making ammonia

Answer 4

. Iron catalyst which is solid in pea sized lumps to increase surface area so the nitrogen and hydrogen can flow over it continuously
The catalyst has to be replaced every 5 years because of catalytic poisoning

. Low pressures and high temperatures give maximum conversion

Question 5

How is ethanol produced

What is the reaction

Answer 5

. Fermentation of sugars eg glucose with the enzymes in yeast as a catalyst

C6H12O6 –> 2C2H5OH +2CO2

It is made by adding water to ethene (so it is a hydration reaction)

. A catalyst used is phosphoric acid absorbed on silica
. Reaction is reversible

Question 6

Uses of ethanol
Where does the ethene come from

Answer 6

. Makes alcoholic drinks
. In cosmetics, drugs, detergents, inks and motor fuel

Main source of ethanol is ethene from crude oil obtained by fractional distillation then cracking

Question 7

What conditions of the reaction will produce the maximum yield of ethanol from ethene

CH2=CH2 + H2O –> CH3CH2OH
ΔH is -46

Answer 7

. A high pressure which will move the equilibrium to the right as there are fewer molecules there

. A low temperature will move equilibrium to the exothermic side to release more heat

. Excess steam will force equilibrium to the right to reduce the steam concentration

Question 8

What are some practical problems with the production of ethanol

Answer 8

. High pressure causes ethene to polymerise to make polyethene

. High pressure is expensive so increases the cost of building the plant and the energy costs of running it

. Low temperature will reduce the rate of reaction and therefore how quickly equilibrium is reached

. Too much steam dilutes the catalyst

Question 9

How is methanol produced

Answer 9

. Made as chemical feedstock , so is a starting material for making other chemicals

. It is made in reaction
CO(g) + 2H2(g) –> CH3OH(g). ΔH=-91

A copper catalyst is used

Methanol can be used as a motor fuel

Question 10

How would the highest yield of methanol be produced

Answer 10

. A highest yield will be given at a low temperature and high pressure