Question

Hydration enthalpy order of compound : ${Li^{+} , Na^{+}, K^{+}, Rb^{+}}$ and ${Cs^{+}}$

• A. $\ce{Li^{+} > Na^{+} > K^{+} > Rb^{+} > Cs^{+} }$
• B. $\ce{Li^{+} < Na^{+} < K^{+} < Cs^{+} < Rb^{+}}$
• C. $\ce{ Na^{+} < K^{+} < Li^{+} < Rb^{+} < Cs^{+} }$
• D. $\ce{ Na^{+} < K^{+} < Li^{+} < Cs^{+} < Rb^{+} }$

Answer 1

Answer: (A)

$\ce{Li^{+} > Na^{+} > K^{+} > Rb^{+} > Cs^{+} }$

Answer 2

Hydration Energy $\propto$ Charge density of cation.