Out of `Cu_(2)Cl_(2)` and `CuCl_(2)`, which is more stable and why?

Explanation

Among `Cu_(2)Cl_(2)` and `CuCl_(2)`, `CuCl_(2)` is more stable. Stability of complex can be explained on the basis of stability of oxidation state of copper. Stability of `Cu^(2+)` (aq) rather than `Cu^(+)` (aq) is due to much more negative value of `[Delta_("hyd")H^(Theta)" of "Cu^(2+) (aq)]` than `Cu^(+)` which more than compensates for the second ionisation enthalpy of `Cu`.