Q33 / 180 · KCET 2022 · Chemistry
All Cu(II) halides are known, except the iodide, the reason for it is that
- Correct answerA$\mathrm{Cu}^{2+}$ oxidises iodide to iodine
- B$\mathrm{Cu}^{2+}$ has much more negative hydration enthalpy
- C$\mathrm{Cu}^{2+}$ ion has smaller size.
- Diodide is bulky ion.
Solution
$2 \mathrm{Cu}^{2+}+4 \mathrm{I}^{-} \longrightarrow 2 \mathrm{CuI}_2$
This $\mathrm{Cu}$ (II) iodide immediately decomposes to liberate $\mathrm{I}_2$ and insoluble copper (I) iodide.
$$
2 \mathrm{CuI}_2 \longrightarrow 2 \mathrm{CuI}+\mathrm{I}_2
$$
Hence, the correct answer is option: 'A'.