Question

1) Mention the conditions to maximise the yield of ammonia by Haber's process

Answer 1

Ammonia is prepared using the Haber’s process.

N2(g) + 3H2(g) –> 2NH3(g) + 22.0 kcal

The conditions required to maximize the yield of ammonia are as follows:

* In accordance to Le Chatelier’s principle ,low temperature will shift the equilibrium to the right because the reaction is exothermic.This gives greater yield of ammonia.Therefore a temperature of about 450°C will be optimal for the preparation of ammonia.

* High pressure on the reaction at equilibrium favours the shift of the equilibrium to the right because the forward reaction proceeds with a decrease in number of moles.Hence a pressure of about 200 atm will be optimal  for the higher yield of ammonia.

* A catalyst should be used to increase the rate of reaction & to quickly attain equilibrium.For eg as iron oxide mixed with small amounts of K2O and Al2O3  can be used as catalyst.
4 N2 & H2 gases should be pure in nature to increase the yield of ammonia.

Hope this helps you...:)

Answer 2

Answer:

In Haber's process, ammonia is formed by the following reaction.

N2(g)+3H2(g)←→−−−−−−−−−Iron oxide (catalyst)2Nh3(g),ΔfH∘=−46.1 kJ mol−1

According to Le-chatelier's principle, the favourable conditions for the maximum yield of ammonia are:

(i) Low temperature : But optimum temperature of 700 K is necessary to keep the forward reaction in progress.

(ii) High pressure : Pressure to the extent of about 200 atm is required.

(iii) Catalyst & promoter : In order to achieve the early attainment of equilibrium, iron oxide acts as catalyst. Along with that : K2O,Al2O3 or Mo metal may act as the promoter to increase the efficiency of the catalyst.