The correct answer is option 4. Mond Process for Refining.
The Mond Process is a method used for refining nickel. It was developed by Ludwig Mond in the late 19th century. This process is specifically employed to purify nickel from impurities, especially those that form volatile compounds.
Here is a detailed explanation of the Mond Process:
1. Formation of Nickel Carbonyl \((Ni(CO)_4)\):
In the first step, finely divided nickel is reacted with carbon monoxide (\(CO\)) at a high temperature (about 50-60°C) under high pressure (about 200 atmospheres). The reaction is as follows:
\[ \text{Ni} + 4\text{CO}\overset{\text{high temperature, high pressure}}{ \longrightarrow} \text{Ni(CO)}_4 \]
2. Formation of Volatile Nickel Carbonyl:
The compound formed, nickel tetracarbonyl (\(Ni(CO)_4\)), is a volatile gas. This allows the removal of impurities that do not form volatile carbonyls. For example, iron, cobalt, and copper do not form such volatile compounds under these conditions.
3. Isolation of Nickel Carbonyl:
The volatile nickel tetracarbonyl is separated from other reaction products and unreacted nickel. This is typically done by cooling the mixture, which causes the nickel carbonyl to condense into a liquid.
4. Decomposition of Nickel Carbonyl to Regenerate Nickel:
The next step involves the decomposition of nickel carbonyl to regenerate pure nickel. This is achieved by heating the nickel carbonyl:
\[ \text{Ni(CO)}_4 \overset{\text{heat}}{\longrightarrow} \text{Ni} + 4\text{CO} \]
5. Recovery of Pure Nickel:
The pure nickel is then recovered, and the carbon monoxide is recycled back to the initial stage of the process.
The Mond Process is especially effective in removing impurities that do not form volatile compounds, leaving behind a highly pure form of nickel. It is commonly used in the industrial production of high-purity nickel for various applications, including the manufacturing of stainless steel and other corrosion-resistant alloys. |
