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CAIE IGCSE Chemistry 6.3.11 Typical Haber & Contact process

CAIE IGCSE Chemistry 6.3.11 Typical Haber & Contact process
Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise explaining why industrial Haber and Contact process conditions balance reaction rate, equilibrium yield, safety and cost.

How this is tested

  • explain how changing temperature or pressure affects rate and equilibrium yield
  • link catalysts to faster forward and reverse reactions without changing equilibrium yield
  • justify why lower temperatures or higher pressures may be impractical or expensive

Question 16

[Maximum number: 1]

The Contact process is used to convert sulfur dioxide to sulfur trioxide. Vanadium(V) oxide is the catalyst in this process.

2SO2( g)+O2( g)⇌2SO3( g)2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_{3}(\mathrm{~g})

The forward reaction in this equilibrium is exothermic.

Which statements about this process are correct?

1 The catalyst increases the rate of both the forward and backward reactions.
2 A low pressure increases the yield of sulfur trioxide.
3 A low pressure is used to keep the costs low.
4 A high temperature increases the yield of sulfur trioxide.

A

1 and 2

B

1 and 3

C

2 and 4

D

3 and 4