(N/A) Henry's law states that at a constant temperature,the partial pressure of a gas in the vapour phase $(p)$ is directly proportional to the mole fraction of the gas $(x)$ in the solution. This is expressed as: $p = K_{H} \cdot x$,where $K_{H}$ is the Henry's law constant.
Explanation:
$1$. The law provides a quantitative relationship between the pressure of a gas and its solubility in a solvent.
$2$. Different gases have different $K_{H}$ values at the same temperature,which depends on the nature of the gas.
$3$. $A$ higher value of $K_{H}$ at a given pressure indicates lower solubility of the gas in the liquid.
$4$. The graph of partial pressure versus mole fraction is a straight line passing through the origin.
Applications:
$1$. To increase the solubility of $CO_{2}$ in soft drinks and soda water,the bottles are sealed under high pressure.
$2$. Scuba divers use tanks filled with air diluted with helium to avoid the toxic effects of high nitrogen concentrations at high pressures (the bends).
$3$. At high altitudes,the partial pressure of oxygen is less than that at the ground level,leading to low blood oxygen levels in climbers,causing weakness and inability to think clearly (anoxia).