SO, we can safely generalize that in the
vast majority of solutions involving a solid solute and a liquid
solvent, the entropy change of the dissolving process is positive.
Magnitudes will vary, of course, but that final value in the
Gibbs-Helmholtz equation is always going to be positive.
Most people know from common experience that
solids seem to dissolve better at higher temperatures (sugar and
salt are both familiar examples). There are exceptions to this
generalization, but there are not a lot and we don't need to
think about them right now. Temperature is clearly a factor and
we can control this factor to encourage (or discourage) the
formation of many solutions.
What we cannot control is the enthalpy change. It's sign and magnitude
therefore become interesting.
Designing an experiment around this topic means
trying to sort out the likely variables that influence the
enthalpy changes in the three hypothetical steps of solution
formation.