Haber and Contact Process

Question 1

Haber Process Formula

Answer 1

N2(g) + 3H2(g) <–> 2NH3(g)

Question 2

Stages of the haber process

Answer 2

1. N2 and H2 are pumped through pipes
2. pressure of mixture increased to 200atms
3. pressurised gases heated to 450C and passed through a tank with iron catalyst
4. reaction mixture is cooled, so ammonia liquefies and is removable
5. unreacted N2 and H2 are recycled

Question 3

Uses of ammonia

Answer 3

fertilisers, explosives, and dyes

Question 4

stage one of the contact process

Answer 4

Making SO2 (not reversible)
Sulfur is burning in air to make sulfur dioxide
sulfur + oxygen –> sulfur dioxide
S(l) + O2(g) –> 2SO2

Question 5

stage two of the contact process

Answer 5

Making SO3 (reversible)
Sulfur dioxide reacts with more oxygen to make sulfur trioxide
sulfur dioxide + oxygen <–> sulfur trioxide
2SO2(g) + O2(g) <–> 2SO3(g)

Question 6

Conditions required for making sulfur trioxide

Answer 6

Vanadium(V) oxide [V2O5] - catalyst
Around 450C (comp temp, decent yield, good ROR)
2atms (increased pressure favours formation of SO3, but if its too high there is a risk of explosion, since SO3 is a highly acidic gas)

Question 7

Stage three of the contact process
(If risks weren’t a thing)

Answer 7

Making H2SO4 (not reversible)
Sulfur trioxide reacts with water to make sulfuric acid
Water + Sulfur trioxide –> sulfuric acid
H2O(l) + SO3(g) –> H2SO4(aq)

Question 8

In industries what is added to the sulfuric acid and why?

Answer 8

Sulfur trioxide is added to highly concentrated sulfuric acid.
Sulfur trioxide + Sulfuric acid –> oleum
SO3 + H2SO4 –> H2S2O7

Stage three is highly exothermic and leads to the formation of sulfuric acid clouds which are very dangerous. So, SO3 is added to form a highly corrosive liquid called oleum to minimise the risk.

Then water is added again to the oleum to form sulfuric acid
H2S2O7 + H2O –> 2H2SO4