Contact process

Question 1

what is the contact process used in

Answer 1

the manufacture or sulfuric acid

Question 2

what are the 2 conditions and catalyst used in stage 2 of the contact process

Answer 2

450℃
2atm
V₂O₅ - vanadium (V) oxide

Question 3

describe stage 1

Answer 3

sulfur is oxidised to form sulfur dioxide

S +O₂ → SO₂

Question 4

describe stage 2

Answer 4

sulfur dioxide is oxidised to sulfur trioxide

SO₂ + O₂ ⇌ SO₃

Question 5

describe stage 3

Answer 5

sulfur trioxide is absorbed into a solution of 98% sulfuric acid to produce a thick liquid called oleum
SO₃ + H₂SO₄ → H₂S₂O₇

oleum is then added to water to produce concentrated sulfuric acid
H₂S₂O₇ + H₂O → 2H₂SO₄

Question 6

why isn’t sulfur trioxide absorbed into water

Answer 6

the reaction will produce a fine mist/gas of sulfuric acid which will be hard to condense and it’s also dangerous

Question 7

why is an optimum temperature of 450 degrees celsius used in stage 2

Answer 7

• the reaction between sulfur dioxide and oxygen is exothermic and high temperatures favour the reverse reaction increasing the yield of reactants and a lower yield of products is produced
• the higher the temperature the lower the yield

Question 8

why are 2atm used in stage 2

Answer 8

a higher pressure will shift the position of equilibrium far to the right producing 96% sulfur trioxide and a mixture of toxic gases
- a higher pressure would increase problems of dealing with the corrosive mixture of gases