In the extraction of nickel by the Mond process, the metal is obtained through thermal decomposition. Let's understand the process in detail:

Mond Process:
The Mond process is a method for the extraction of nickel from its ores. It was developed by Ludwig Mond, a German chemist, in the late 19th century. This process involves the conversion of nickel oxide (NiO) into pure nickel (Ni) through a series of chemical reactions.

Thermal Decomposition:
In the Mond process, thermal decomposition plays a crucial role in obtaining nickel. Thermal decomposition is a chemical reaction in which a compound is broken down into simpler substances by the action of heat.

Step-by-Step Process:
1. Initially, nickel oxide (NiO) is obtained from the nickel ore, which is a compound of nickel and oxygen.
2. The nickel oxide is then heated in the presence of a stream of pure carbon monoxide (CO) gas.
3. The following reaction takes place:
NiO + CO → Ni + CO2
In this reaction, carbon monoxide acts as a reducing agent, which removes oxygen from nickel oxide and produces pure nickel metal.
4. The reaction is carried out at a high temperature of around 400-450°C and under controlled pressure.
5. The carbon monoxide gas is continuously passed over the nickel oxide, ensuring the completion of the reaction.
6. The resulting nickel metal is then cooled and collected.

Advantages of the Mond Process:
- The Mond process is highly efficient and allows the extraction of pure nickel metal.
- It is a relatively simple and cost-effective method compared to other extraction processes.
- The process can be carried out on a large scale, making it suitable for industrial production.

Conclusion:
In conclusion, the extraction of nickel by the Mond process involves the thermal decomposition of nickel oxide. By heating the nickel oxide in the presence of carbon monoxide gas, the oxygen is removed, and pure nickel metal is obtained. This process is widely used for the commercial extraction of nickel due to its simplicity and efficiency.