Discuss the application of LE Chatellier's principle for the industrial synthesis of Ammonia and sulphur trioxide.

Explanation

Applications of Le Chatelier.s principle to synthesis of Ammonia by Haber.s process":
`underset(4 "volumes" (N_(2)(g)+3H_(2)g) hArr underset("2 volumes")(2NH_(3)g), DeltaH=-92 kJ`
Nitrogen and Hydrogen combine to form ammónia. The formation of ammonia is reversible and exothermic reaction. It is accompanied by decrease in volume.
Effect of Pressure : 1 volume of `N_(2)` combines.with 3 volumes of `H_(3)` to form 2 volumes of `NH_(3)` . There. is decrease in volume in the forward reaction (4 volumes to 2 volumes). According to Le Chatelier.s principle increase of pressure favours the reaction where there is decrease in volume, So higher the pressure, greater the yield of ammonia. In practice 200 atmospheres are used in the manufacture of ammonia by Haber.s process.
Low pressures favour the reverse reaction i.e., decomposition of `NH_(3)` already formed.
Effect of Temperature : The formation of ammonia (forward reaction) is exothermic reaction.
`N_(2)+3H_(2) to 2NH_(3), DeltaH=-92 kJ`
Low temperatures favour the forward reaction. But at low temperatures the reaction.is too slow.. Therefore an optimum temperature (725 K - 775 k) is chosen.in Haber.s process. To speed up the reaction, a catalyst, finely divided iron is used. To increase the activity of the catalyst molybdenum or a mixture of oxides of K and Al is used as promoter.
The reverse reaction (i.e.,) decomposition of `NH_(3)` is an endothermic reaction. High temperatures favour the decomposition of `NH_(3)` Therefore high temperatures are avoided in Haber.s process. Thus the optimum conditions are

Application of Le Chatelier.s principle to the synthesis of `SO_(3)`:
`underset("3 volumes" (2+1))(2SO_(g)+O_(2)(g)) hArr underset("2 volumes")(2SO_(3)(g), DeltaH)=-189kJ`
The formation of `SO_(3)` is reversible and exothermic reaction. It is accompanied by decrease in volume. 1. Effect of Pressure : 2 volumes of `SO_(3)` and one volume of `O_(2)` combine to give 2 volumes of `SO_(3)` According to Le Chatelier.s Principle increase of pressure favours the reaction where there is decrease in volume. The formation of `SO_(3)` is accompanied by decrease in volume (3 volumes to 2 volumes). Higher the pressure.greater is the yield of `SO_(3)` But in contact process high pressures are not used because towers used in the manufacture are corroded by the acid at these high pressures.
Low pressurés favour the decomposition of `SO_(3)` as there is increase in the volume of (2 volumes to 3 volumes). Therefore optimum pressures are used (1.5 to 1.7 atmosphere)..
2. Effect of Temperature : The formation of `SO_(3)` is exothermic. 189.kl of heat, is evolved. High temperatures favour the reverse reaction which is endothermic and do not favour the forward reaction which is exothermic. Low temperatures are favourable for the formation of `SO_(3)` At low temperature the reaction is too slow. Therefore an optimum temperature 673 K is used. To speed up the reaction `V_(2)O_(5)` is used as catalysta . . Thus the optimum conditions are