Question

The correct order of hydration enthalpies of alkali metal ions is -

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

Answer 1

Answer: (A)

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

Answer 2

Hydration enthalpy depends upon ionic potential (charge / size). As ionic potential increases hydration enthalpy increases.