Explain4 marksStandard
The table below shows some enthalpy data for sodium chloride and magnesium chloride.
| Compound | Lattice enthalpy / kJ mol⁻¹ | Hydration enthalpy of cation / kJ mol⁻¹ | Hydration enthalpy of chloride ion / kJ mol⁻¹ |
|---|---|---|---|
| NaCl | -770 | -410 | -350 |
| MgCl₂ | -2500 | -1900 | -350 |
The hydration enthalpy of the chloride ion is the same for both compounds. Explain why the enthalpy change of solution of magnesium chloride is more exothermic (more negative) than that of sodium chloride. Use an energy cycle in your explanation.