Chapter 17, Problem 30E

(a)

Interpretation Introduction

Interpretation: The enthalpy of hydration for calcium chloride and calcium iodide needs to be determined.

Concept Introduction : According to Hess’s law, the overall enthalpy is the summation of individual enthalpies:

  $\Delta H=\Delta H_1+\Delta H_2+\Delta H_3\mathrm{......}$

(b)

Interpretation Introduction

Interpretation: The ion, among ${\text{Cl}}^{\text{-}}$ or , ${\text{I}}^{\text{-}}$ which is more strongly attracted to water needs to be determined.

Concept Introduction : Hydration energy is the amount of energy evolved when hydration one mole of ions takes place. The heat released due to formation of new bonds with water molecules is termed as the hydration enthalpy. Hydration enthalpy is always negative.

The elements with larger negative value of enthalpy of hydration are easily hydrolyzed than that of the element with lower negative value of enthalpy of hydration.