NEET · Chemistry · STD 12 - 4. d and f- block elements

The stability of \(Cu ^{2+}\) is more than \(Cu ^{+}\)salts in aqueous solution due to -

A second ionisation enthalpy.
B first ionisation enthalpy.
C enthalpy of atomization.
D hydration energy.

Verified Solution

Answer & Solution

Correct Answer

(D) hydration energy.

Step-by-step Solution

Detailed explanation

The stability of \(Cu ^{2 +}( aq )\) is more than \(Cu ^+ ( aq )\) is due to the much more negative \(\Delta_{\text {hyd }} H^{\circ}\) of \(Cu ^{2+}( aq )\) than \(Cu ^{+}( aq )\), which more than compensates for second ionisation enthalpy of \(Cu\). \(\Delta \text { hyd } H ^{\circ} \text { of } Cu ^{2+}( aq )=-2121\,kJ\,mol ^{-1}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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