Henry's law

Henry's law Information about the mass fraction of the “air/gas content” that is undissolved is given by Henry’s law.

The lowest pressure at which, in equilibrium, all air/gas is dissolved is called the saturation pressure.

• Above this pressure, in equilibrium, all the air/gas is dissolved.

• Below this pressure (according to Henry’s law) the fraction of air/gas that is undissolved varies linearly with absolute pressure.

We can slightly modify Henry’s law so that the mass fraction of air/gas that is undissolved varies between the two pressures parameters Psat and PHvap.

Figure 1: Modified Henry’s law