Chapter 19 — Chapter 19 — Nitrogen and Sulphur

N₂ from fractional distillation of liquid air (N₂ b.p. −196 °C boils off before O₂ −183 °C). H₂ from methane by steam reforming: CH₄ + H₂O → CO + 3H₂ (Ni catalyst, ~800 °C); CO + H₂O → CO₂ + H₂. N₂ + 3H₂ ⇌ 2NH₃ (exothermic): 450 °C, 200 atm, iron catalyst. High temperature is used because the activation energy is very high (rate too slow at low temperature) — a compromise with yield; unreacted gases recycled; NH₃ removed by cooling/liquefying. Ammonia is important for fertilizers (urea, ammonium nitrate), nitric acid, explosives, refrigerant, cleaning agents, nylon.