Haber and Contact Process
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Haber Process Formula
N2(g) + 3H2(g) <–> 2NH3(g)
Stages of the haber process
• N2 and H2 are pumped through pipes • pressure of mixture increased to 200atms • pressurised gases heated to 450C and passed through a tank with iron catalyst • reaction mixture is cooled, so ammonia liquefies and is removable • unreacted N2 and H2 are recycled
Uses of ammonia
fertilisers, explosives, and dyes
stage one of the contact process
Making SO2 (not reversible) Sulfur is burning in air to make sulfur dioxide sulfur + oxygen –> sulfur dioxide S(l) + O2(g) –> 2SO2
stage two of the contact process
Making SO3 (reversible) Sulfur dioxide reacts with more oxygen to make sulfur trioxide sulfur dioxide + oxygen <–> sulfur trioxide 2SO2(g) + O2(g) <–> 2SO3(g)
Conditions required for making sulfur trioxide
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)
Stage three of the contact process (If risks weren’t a thing)
Making H2SO4 (not reversible) Sulfur trioxide reacts with water to make sulfuric acid Water + Sulfur trioxide –> sulfuric acid H2O(l) + SO3(g) –> H2SO4(aq)
In industries what is added to the sulfuric acid and why?
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