Question

1) Determine the general pressure and temperature conditions needed to obtain the optimum yield of nitric oxide by oxidation of ammoia:

4 NH3 (g) + 5 O2 (g) ⇌ 4 NO (g) + 6 H2O (g) ; △H∘ < 0

Answer 1

To understand the effect of pressure anf temperature on the given reaction we can make use of Le Chatelier's principle

It can be applied to predict the effect of change in conditions at equilibrium.

Effect of temperature.

dH of the system is negative. Hence the given reaction is exothermic reaction. Now If we increase the temperature of the system, the heat content of system , in general, would increase, and the system would try to consume this additional heat by shifting the reaction to left hand side. As a result of this less, nitric oxide will be formed.But this will not be the case when temperature is low .

Hence Low temperature will favour the formation of nitric oxide which will help to obtain the optimm yield of nitric oxide

Effect of pressure.

To understand the effect effect of pressure observe the total number of moles on left hand side and right hand sde

Total number of moles on left hand side: 4+5 =9

Total number of moles on right hand side:4+6=10

Whenever pressure is increase the side with lesse number of moles is preffered. Hence , if we increase the pressur, since the left had side has 9 moles, the reaction would shift to Left hand side forming less number of nitric acid moles.

Hence , Lower pressure will shift the reaction to right hand side, resulting in formation of nitric acid. Thus increasing the yield of nitric acid