Question

Which of the following will favour the formation of $N{H}_3$​ by Haber's process?

• A. Decrease in temperature
• B. Increase in pressure
• C. Addition of catalyst
• D. All of the above

Answer 1

The correct option is D All of the above

(a) Formation of ammonia from nitrogen and hydrogen is an exothermic process. At low temperature, the reaction proceeds in forward direction so that more of ammonia is obtained. This will produce heat and nullify the effect of low temperature.

(b) The formation of ammonia proceeds with decrease in the number of moles of gaseous species. When pressure is high, the reaction will proceed in the forward direction so that the effect of increased pressure is nullified.

(c) The activation barrier for the dissociation of $N_2$ and $H_2$ in​ the gas phase is very high.​ Without a catalyst, the reaction between $N_2$ and $H_2$ occurs slowly.​ In the presence of a suitable​ catalyst such as Fe, the dissociation of $N_2$ and $H_2$ to give adsorbed atoms is facile.​