What Is Henry Law For Solubility of a Gas

The quantitative relation of pressure effect on solubility of gases was given by Henry, which is called Henry Law.

According to Henry's law, the solubility of a gas at a constant temperature is proportional to the pressure of that gas.

Therefore m ∝ P
or m = kP

Here is
m = amount of dissolved gas
P = gas pressure in equilibrium
k = proportionality constant.

If solubility is expressed in mole fraction of a gas in solution, then

 According to Henry's law, the partial pressure (p) of a gas in its vapor state is proportional to the mole fraction (X) of gas in that solution.

ie  p ∝ Xɢᴀs
either p = Kₕ Xɢᴀs

Here K is called Henry's constant.

 If a graph is drawn between the partial pressure (p) and the mole fraction (X) of a gas, a straight line is obtained whose slope represents Kₕ.