The Haber Process
The Haber process is used to make ammonia NH3
Uses of ammonia include:
- Making fertilisers
- Making nitric acid
- Making nylon
The equation for the reaction is:
N2 + 3H2 2NH3 ∆H = -92 kJ mol-1
- The forward reaction would be favoured by a low temperature because the forward reaction is exothermic (so lowering the temperature would cause the reaction to make more NH3 to heat things up abit more). 450ºC isn’t a low temperature. It is however, a compromise temperature, because if the temperature was made to be low, the reaction would be so slow that it would take a very long time to produce much ammonia.
- Pressure is also another compromised. Because the forward reaction has less molecules than the back reaction (2 molecules of NH3 as opposed to 1 N2 and 3 H2 molecules), the forward reaction would be favoured by a high pressure. 200 atm is high, but anything higher would be extremely expensive.
- The iron catalyst speeds the reaction up but has no effect on the equilibrium. However, if the catalyst wasn’t used, the reaction would be too slow.