Q.Describe a method for refining nickel.

Step 1. The Mond process is a vapour phase refining method: the impure metal is first converted, by reaction with a chosen reagent, into a compound that is VOLATILE, while the solid impurities present do not form this volatile compound and are left behind.

Step 2. For nickel, the impure metal is heated in a stream of carbon monoxide gas at around 350 K. Nickel reacts with CO to form nickel tetracarbonyl, a highly volatile compound: Ni(s) + 4CO(g) → Ni(CO)4.

Step 3. Because Ni(CO)4 is volatile, it is carried away from the solid impurities (which are not converted to any volatile CO compound) and transported to a separate, hotter part of the apparatus. …

Describe the Mond process's two-temperature cycle (lower T forms the volatile carbonyl, higher T …

• Reversing the two temperatures -- the LOWER temperature (~350 K) is used to FORM the volatile Ni(CO)4 compound, and the HIGHER temperature (~460 K) is used to DECOMP …