1
In which of the following processes, fused sodium hydroxide is electrolysed at a temperature of 330 C for extraction of sodium?
- Castner's process
- Downs process
- Cyanide process
- Both (2) and (3)
Answer
(1) Castner's process
Solution
In Castner's process, fused NaOH is electrolysed at about 330 C (iron cathode, nickel anode):
Cathode: Na+ + e- Na
Anode: 4OH- 2H2O + O2 + 4e-
Downs process: electrolysis of fused NaCl (mixed with CaCl2) — the present commercial method for sodium.
Cyanide process: extraction of silver and gold by leaching with NaCN solution.
∴ The process is Castner's process.
Answer: (1)
Out of syllabusAIPMT 2002