Question

State Henry’s law. State the relationship between Henry’s law constant and solubility of a gas.

Answer 1

Hint: Maximum solubility of the solute which can be dissolved in a specified amount of solvent at a constant temperature is known as the solubility of the solute in the solvent. It is affected by the nature of solute as well as the nature of the solvent. It is also affected by the temperature and the pressure.

Complete step by step answer:
There are various definitions that fit with Henry's law. They can be stated as:
“Henry’s law can be stated as at constant temperature, the solubility of a gas in a particular liquid is directly proportional to the partial pressure of the gas present above the surface of the liquid.” or,
“The mole fraction of a gas in the solution is proportional to the partial pressure of the gas over the solution.” Or,
“The partial pressure of the gas in vapor phase ($P$ ) is proportional to the mole fraction of the gas ($x$ ) in the solution." According to this definition,
$P = {K_H}x$
Where, ${K_H} = $ Henry’s constant
The law states that at a constant temperature, the solubility (\[S\] ) of a gas in a liquid is directly proportional to the pressure (\[P\] ) of the gas. Thus the solubility of gas at unit pressure is equal to Henry's constant.
$S = {K_H}P$
Thus, when ${K_H} = 1$, $S = P$ .

Note:
Henry’s constant is not a universal constant. It depends upon the nature of the gas and the temperature. Henry’s constant increases with an increase in the temperature. Therefore, the solubility of the gas decreases. Increasing the pressure increases the solubility and increase in temperature decreases the solubility of the gas in the liquid.