The value of the heat of solution for a substance result form an interplay of

Options

A. solvent-solvent interactions
B. solute-solute interactions
C. solvent-solute interactions
D. All of these

Answer

4

Explanation

It results from an interplay of all three kinds of interaction:
Energy is required (`DeltaH` is positive) to overcome intermolecular forces between solvent molecules because the molecular must be separted and pushed apart to make room for solute particles.
Energy is required (positive `DeltaH`) to overcome intermolecular forces holding solute particles together in a crystal. For an ionic solid, this is the lattice enthalpy. Therefore, subdtances with higher lattice enthalpies tend to be less solute than substances with lower lattice enthlpies.
Energy is released (negative `DeltaH`) when solvent molecules cluster around solute particles and solvent them. For ionic compounds in water, the amount of hydration enthalpy released is generally greater for smaller cations than for larger ones because water molecules can approach the positive nuclei of smaller ions more closely and thus bind more tightly. In addition enthalpy generally increases as the charge on the ion increases.