Answer: Nickel: Ni + 4CO → Ni(CO) 4 (volatile) at 50-60°C; decomposed at 180-230°C to deposit pure Ni.
- A Nickel: Ni + 4CO → Ni(CO)<sub>4</sub> (volatile) at 50-60°C; decomposed at 180-230°C to deposit pure Ni
- B Iron, which is instead purified by oxidation in a Bessemer-type converter in many documented cases
- C Copper, which is instead purified by electrolytic refining according to conventional understanding
- D Zinc, which is instead purified by fractional distillation in routine practice overall
Correct answer: A. Nickel: Ni + 4CO → Ni(CO)<sub>4</sub> (volatile) at 50-60°C; decomposed at 180-230°C to deposit pure Ni
Explanation: The Mond process forms nickel carbonyl (volatile) from impure Ni and CO; it is transported and decomposed at higher temperature to deposit pure Ni.
An Ellingham diagram plots ΔG° of oxide formation against temperature for different metals; whichever line is LOWER (more negative ΔG°) at a given temperature reduces the oxide of any metal whose line sits above it - the basis of carbon reduction (Fe, Zn) vs electrolytic reduction (Al, Mg, Na) decisions.
Concept context
The science of extracting metals from ores and refining them for use. Covers concentration methods, reduction techniques, refining processes, and the thermodynamic principles that govern metal extraction.