Editing Solubility (section)

===Pressure===
For condensed phases (solids and liquids), the pressure dependence of solubility is typically weak and usually neglected in practice. Assuming an [[ideal solution]], the dependence can be quantified as:

:<math> \left(\frac{\partial \ln N_i}{\partial P} \right)_T = -\frac{V_{i,aq}-V_{i,cr}} {RT} </math>

where the index <math>i</math> iterates the components, <math>N_i</math> is the mole fraction of the <math>i</math>-th component in the solution, <math>P</math> is the pressure, the index <math>T</math> refers to constant temperature, <math>V_{i,aq}</math> is the [[partial molar volume]] of the <math>i</math>-th component in the solution, <math>V_{i,cr}</math> is the partial molar volume of the <matH>i</math>-th component in the dissolving solid, and <math>R</math> is the [[universal gas constant]].<ref>{{cite book|author=E.M. Gutman| title=Mechanochemistry of Solid Surfaces|publisher= World Scientific Publishing Co.|year=1994}}</ref>

The pressure dependence of solubility does occasionally have practical significance. For example, [[Fouling#Precipitation fouling|precipitation fouling]] of oil fields and wells by [[calcium sulfate]] (which decreases its solubility with decreasing pressure) can result in decreased productivity with time.