State Henry’s law.
Henry’s law: The mass of a gas dissolved in a given volume of the liquid at constant temperature is directly proportional to the pressure of the gas present in equilibrium with the liquid.
Henry’s law relates solubility of a gas with external pressure. The law states that, “the
solubility of a gas in liquid at constant temperature is proportional to the pressure of
the gas above the solution”.
f S is the solubility of the gas in mol dm−3, then according to Henry’s law,
S ∝ P i.e. S = KP
where, P is the pressure of the gas in atmosphere, K is constant of proportionality and
has the unit of mol dm−3 atm−1.