Conditions which affect the haber process and compromises made to increase production of ammonia:
Decrease in temperature - System moves to increase temperature by favouring the exothermic reaction as this releases heat energy. POE moves to the right, increasing the amount of ammonia produced.
Increase in pressure - System moves to decrease pressure by favouring the reaction that produces fewest gas molecules. POE moves to the right, increasing the amount of ammonia produced.
The actual conditions used to in the Haber process are a compromise. Ideally a low temperature and a high pressure (as discussed above) would favour a high yield of ammonia. However, the reaction would be too slow with a low temperature so ~500 C is used. A high pressure would be dangerous and expensive, so 200 atm is used. An iron catalyst is used to increase the rate at which equilibrium is formed.
Sulfur trioxide reacts with sulfuric acid to form a compound called oleum which when added to water forms sulfuric acid. (If sulfur trioxide is added directly to water an extremely corrosive fog of sulfuric acid is formed, so dissolving it in pre-made concentrated sulfuric acid is most manageable.
For the above reaction, high pressure and low temperature would favour the equilibrium production of sulfur trioxide but the high pressure is uneconomical and the low temperature is too slow. A compromise of atmospheric pressure and a temperature of 450 C gives a very high yield of sulfur trioxide.
© Copyright rmcstudy