Henry's Law describes the relationship between the solubility of a gas in a liquid and the pressure of that gas above the liquid. Specifically, it states that the solubility of a gas is directly proportional to the pressure exerted by that gas. This principle is crucial in understanding how gases dissolve in liquids under varying conditions.

In the context of the 2.4 method, the formula can be expressed as:

\(\frac{S_1}{P_1} = \frac{S_2}{P_2}\)

Here, \(S_1\) represents the initial solubility of the gas, \(P_1\) is the initial pressure, \(S_2\) is the final solubility, and \(P_2\) is the final pressure. This version of Henry's Law is particularly useful when comparing two different solubilities at two distinct pressures for a given gas.

The solubility can be measured in various units, including molarity (moles per liter) or other mass per volume units, allowing for flexibility in application across different scenarios. Understanding this relationship is essential for fields such as chemistry, environmental science, and engineering, where gas solubility plays a critical role in processes like carbonation, respiration, and pollutant behavior in aquatic systems.