Question

Describe the method of preparation of dinitrogen in the laboratory and also write the chemical equations of the reactions. Write the reactions of dinitrogen with (i) oxygen and (ii) magnesium at high temperature. What is its reaction with hydrogen in presence of catalyst at 773 K temperature?

Hint:

The Haber process, which uses a catalyst at 773 K to combine nitrogen and hydrogen, is essential for industrial ammonia production.

Answer 1

Step 1: Preparation of Dinitrogen.
Dinitrogen is prepared in the laboratory by heating ammonium nitrite (\(\text{NH}_4\text{NO}_2\)) or by passing ammonia gas over heated copper oxide. The chemical equations for these processes are: \[ \text{NH}_4\text{NO}_2 (aq) \rightarrow \text{N}_2 (g) + 2 \text{H}_2\text{O} (l) \] or \[ 2 \text{NH}_3 (g) + 3 \text{CuO} (s) \rightarrow \text{N}_2 (g) + 3 \text{Cu} (s) + 3 \text{H}_2\text{O} (g) \]
Step 2: Reaction of Dinitrogen with Oxygen.
When dinitrogen reacts with oxygen at high temperatures, it forms nitrogen monoxide (NO): \[ \text{N}_2 (g) + \text{O}_2 (g) \rightarrow 2 \text{NO} (g) \]
Step 3: Reaction of Dinitrogen with Magnesium.
At high temperatures, dinitrogen reacts with magnesium to form magnesium nitride (Mg\(_3\)N\(_2\)): \[ \text{N}_2 (g) + 3 \text{Mg} (s) \rightarrow \text{Mg}_3\text{N}_2 (s) \]
Step 4: Reaction of Dinitrogen with Hydrogen.
At 773 K, in the presence of a catalyst (such as iron), dinitrogen reacts with hydrogen to form ammonia: \[ \text{N}_2 (g) + 3 \text{H}_2 (g) \xrightarrow{\text{catalyst}} 2 \text{NH}_3 (g) \]