Q69 / 180 · AIIMS 2007 · Chemistry

Cyanogen gas is obtained in the reaction

  • Correct answer
    A
    \(\mathrm{CuSO}_{4(a q)}+\mathrm{KCN} \longrightarrow\)
  • B
    \(\mathrm{K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right] \stackrel{\text { heat }}{\longrightarrow}\)
  • C
    \(\mathrm{CH}_3 \mathrm{CN}+\mathrm{H}_2 \mathrm{O} \stackrel{\Delta}{\longrightarrow}\)
  • D
    \(\mathrm{CH}_3 \mathrm{CONH}_2+\mathrm{P}_2 \mathrm{O}_5 \stackrel{\Delta}{\longrightarrow}\)

Solution

\(2 \mathrm{CuSO}_4+4 \mathrm{KCN} \rightarrow(\mathrm{CN})_2+2 \mathrm{CuCN}+2 \mathrm{~K}_2 \mathrm{SO}_4\) On combining solution of copper (II) salts and cyanides, an unstable copper (III) cyanide is formed which rapidly decomposes into copper (I) cyanide and cyanogen.

Hence, the correct answer is option: 'A'.

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