Question:
Explain why Cu+ ion is not stable in aqueous solutions?
Solution:
In an aqueous medium, Cu2+ is more stable than Cu+. This is because although energy is required to remove one electron from Cu+ to Cu2+, high hydration energy of Cu2+ compensates for it. Therefore, Cu+ ion in an aqueous solution is unstable. It disproportionates to give Cu2+ and Cu.
$2 \mathrm{Cu}_{(a q)}^{+} \longrightarrow \mathrm{Cu}_{(a q)}^{2+}+\mathrm{Cu}_{(s)}$