Which factor is most important when predicting trends in the enthalpy of solution for ionic compounds?

• A. The color of the compound in solution
• B. The boiling point of the solvent
• C. The atomic number of the metal ion
• D. The lattice energy and hydration enthalpy of the ions

Answer: (D)

Verified step by step guidance

1. Understand that the enthalpy of solution for ionic compounds depends primarily on the energy changes involved when the ionic solid dissolves in a solvent, usually water.
2. Recognize that two main energy factors influence this process: the lattice energy of the ionic solid and the hydration enthalpy of the ions formed when the solid dissolves.
3. Lattice energy is the energy required to separate one mole of an ionic solid into its gaseous ions, reflecting the strength of the ionic bonds in the solid.
4. Hydration enthalpy is the energy released when gaseous ions are surrounded by water molecules and stabilized in solution.
5. Therefore, predicting trends in the enthalpy of solution involves comparing the magnitude of lattice energy and hydration enthalpy, as these determine whether the dissolution process is endothermic or exothermic.