According to Henry's Law, how does the vapor pressure of a target substance relate to its mole fraction in water treatment?

Henry's Law states that the amount of dissolved gas in a liquid at a given temperature is directly proportional to the partial pressure of that gas above the liquid. In the context of water treatment and vapor pressure, this means that as the mole fraction of the target substance increases, the vapor pressure also increases proportionally. This relationship is particularly important in processes that involve the transfer of gases between the liquid and vapor phases, such as in aeration or removal of volatile contaminants from water.

In practical terms, if you have a gas dissolved in water and you increase the concentration (mole fraction) of that gas, the vapor pressure of the gas above the solution will increase as well. This is because more gas particles in the solution lead to more gas particles escaping into the vapor phase, thus elevating the vapor pressure.

The relationship is crucial for understanding gas solubility and the behavior of volatile compounds in aquatic systems, influencing design and operation decisions in water treatment processes. This direct proportionality underlines many environmental engineering applications, particularly in estimating how pollutants behave in aquatic environments.