 Although the reduction of temperature to microscopic properties is problematic, it is a relatively easy candidate for reduction. Properties concerned with chemical changes such as phase transitions, solubility, and reactivity, are considerably more complex. As we discussed in Section 4.5, a purely microscopic description of matter is not coextensive with all chemical properties. Solubility, for example, is not fully explained by microscopic properties. While we can explain in rough qualitative fashion that substances dissolve when their ions or molecules have more affinity for the solvent than they do for each other, this doesn’t recover the subtle, quantitative features of solubility. It also leaves the solubility of nonionic substances untouched. Predicting these features requires appeals to thermodynamics, and the alleged reduction of thermodynamics to statistical mechanics is considered highly contentious (Sklar 1993).