Question

State Henry's law. Why do gases always tend to be less soluble in liquids as the temperature is raised?

Answer 1

According to Henry's law, "the partial pressure of a gas in vapour phase (p) is directly proportional to the mole fraction of gas in the solution." e.g., For a gas A
$p_A=k_H\times x_A$
where $k_H$ is called Henry's constant.
It may be noted that the dissolution of a gas in a liquid is exothermic process.

Gas + Solvent $\rightleftharpoons$ Solution + Heat

According to Le Chatelier's principle, increase in temperature will favour the equilibrium in the backward direction i.e., solubility of gas will decrease. In other words, gases always tend to be less soluble in liquids as the temperature is raised.