Cyanamide is prepared by the cyanamide process. The cyanamide process involves the reaction of calcium carbide (CaC2) with nitrogen gas (N2) to produce calcium cyanamide (CaCN2), which can then be hydrolyzed to form cyanamide (NH2CN).

The process can be summarized as follows:

1. Preparation of Calcium Carbide:
Calcium carbide is synthesized by heating lime (CaO) and coke (carbon) in an electric arc furnace. The chemical equation for this reaction is:
CaO + 3C → CaC2 + CO

2. Reaction with Nitrogen Gas:
The calcium carbide produced in the first step is then reacted with nitrogen gas in a reactor at high temperatures (around 1000-1200°C) and under pressure. The chemical equation for this reaction is:
CaC2 + N2 → CaCN2

3. Hydrolysis of Calcium Cyanamide:
The calcium cyanamide obtained from the previous step is then hydrolyzed with water to yield cyanamide. The hydrolysis reaction takes place in the presence of a catalyst, usually sulfuric acid. The chemical equation for this reaction is:
CaCN2 + 3H2O → CaCO3 + 2NH3 + H2S

Key Points:
- Cyanamide is prepared by the cyanamide process.
- The process involves the reaction of calcium carbide with nitrogen gas to produce calcium cyanamide, which can then be hydrolyzed to form cyanamide.
- Calcium carbide is synthesized by heating lime and coke in an electric arc furnace.
- The reaction between calcium carbide and nitrogen gas takes place at high temperatures and under pressure.
- The hydrolysis of calcium cyanamide is carried out in the presence of a catalyst, usually sulfuric acid.

In conclusion, cyanamide is prepared by the cyanamide process, which involves the reaction of calcium carbide with nitrogen gas followed by hydrolysis of the resulting calcium cyanamide.