Question

(a) Use the following data to calculate the to calculate the enthalpy of hydration for calcium chloride and calcium iodide.

(a) Based on your answer to part (b) which ion Cl^- or I^- is more strongly attracted to water?

Short answer

1. Enthalpy of hydration for CaCl₂ is $-2293\text{kJ/mol}$ and Enthalpy of hydration for CaI₂ is $-2163\text{kJ/mol}$
2. Chloride ion is more strongly attracted to water than Iodide ion.

Step-by-step solution

Step1- Enthalpy of hydration

It is defined as the quantity of energy released when 1 mole of gaseous ion is diluted.

Its formula is$∆{\mathrm{H}}_{\mathrm{hyd}}=∆{\mathrm{H}}_{\mathrm{solution}}+∆{\mathrm{H}}_{\mathrm{LE}}$

For CaCl₂

$$\begin{gathered} ∆{\mathrm{H}}_{\mathrm{hyd}}=-46\text{kJ/mol}+\left(-2247\text{kJ/mol}\right) \\ =-2293\text{kJ/mol} \end{gathered}$$

For CaI₂

$$\begin{gathered} ∆{\mathrm{H}}_{\mathrm{hyd}}=-104\text{kJ/mol}+\left(-2059\text{kJ/mol}\right) \\ =-2163\text{kJ/mol} \end{gathered}$$

Step 2- Attracted toward the water

From the calculation, we can see that the enthalpy of hydration of calcium chloride is more than calcium iodide therefore we can conclude that chloride ions are attracted to the water.