The greater the vapor pressure, the greater number of organic molecules that volatilize. Vapor pressure can be thought of as the solubility of a molecule in a gas. The volatilization of a non-aqueous liquid is measured in terms of Raoult's Law while the volatilization of a dissolved organic molecule is measured in terms of Henry's Law. The solution, precipitation, complex formation, hydrolysis, sorption activities, reduction-oxidation reactions of solids are highly important in the generation of ground water quality. Ground water, especially of a more acidic pH, is capable of dissolving minerals.
Congruent solution occurs when a mineral is totally dissolved in the ground water.
Incongruent solution occurs when the mineral and water react but leave a new solid along with parts of the old mineral in solution. Congruent Solution Halides, sulfate, carbonate minerals dissolve quite readily, over relatively short periods of time, in acidic ground water. In addition, quartz and gibbsite also dissolved by in much smaller concentrations and over greater spans of time. The feldspars and many of the dark silicate minerals dissolve and undergo hydrolysis, the reaction of a mineral with water. These reactions are incongruent in that there is a new solid phase produced by the reaction.