Question

Explain the industrial preparation of ammonia by Haber’s process. Also, write two physical properties of ammonia.

Answer 1

Hint: To answer this question we should be describing the Haber’s process. The reaction, the catalyst used and the reason behind it should be mentioned as the answer. The Haber’s process is important because it was the first of the processes developed that allowed people to mass produce plant fertilizers due to the production of Ammonia.


Complete step by step solution:
We should know that on an industrial scale, ammonia is prepared by Haber’s process. The constituents of ammonia ${{\text{N}}_{\text{2}}}$and ${{\text{H}}_{\text{2}}}$combine in a ratio of 1:3.

The reaction is given below:
${{\text{N}}_{\text{2}}}\text{+ 3}{{\text{H}}_{\text{2}}}\text{ 2N}{{\text{H}}_{\text{3}}}$
The reaction proceeds in the forward direction with a remarkable decrease in volume and thus the reaction is exothermic. In accordance with Le Chatelier’s principle, high pressure would favour the formation of ammonia. The optimum conditions for the production of ammonia at a pressure of approximately 200 atm, a temperature of approximately 700 K and the use of a catalyst such as iron oxide with small amounts of ${{\text{K}}_{\text{2}}}\text{O}$ and $\text{A}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}$ to increase the rate of attainment of equilibrium.
We know that catalysts do not change the equilibrium concentrations of reacting substances in reversible reaction. However, they do reduce the time taken to reach equilibrium. Iron is a cheap catalyst used in the Haber’s process. It helps to achieve an acceptable yield in an acceptable time.

Two physical properties of Ammonia are as follows:
Ammonia is very soluble in water, but it ionises partially in water to form a weak alkali. A 0.1 mol $d{{m}^{-3}}$ammonia solution has a pH of about 10.
Ammonia being alkaline can undergo neutralisation with acids to form ammonium salts.
Ammonia + Acid $\to $Ammonium salt.

For example:
$\text{2N}{{\text{H}}_{\text{3}}}\text{(aq) + }{{\text{H}}_{\text{2}}}\text{S}{{\text{O}}_{\text{4}}}\text{(aq) }\xrightarrow{{}}\text{ (N}{{\text{H}}_{\text{4}}}\text{)2S}{{\text{O}}_{\text{4}}}\text{(aq)}$$\text{2N}{{\text{H}}_{\text{3}}}\text{(aq) + }{{\text{H}}_{\text{2}}}\text{S}{{\text{O}}_{\text{4}}}\text{(aq) }\xrightarrow{{}}\text{ (N}{{\text{H}}_{\text{4}}}\text{)2S}{{\text{O}}_{\text{4}}}\text{(aq)}$
Ammonia neutralises sulphuric acid to form ammonium sulphate.


Note: So we know that in the Haber’s process there is the reaction between nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia. The reaction is reversible and the production of ammonia is exothermic. The catalyst is actually slightly more complicated than pure iron.