Henry's Law: Statement, Formula, Application & Limitation

Henry's Law

Henry's Law: In Physical Chemistry, Henry's law is a gas law that states that "The amount of dissolved gas in a liquid is directly proportional to the partial pressure of the gas above the liquid at constant temperature" Here proportionality factor is known as Henry's law constant. Henry's constant is denoted by Kh. This concept of Henry's Law was formulated by English chemist William Henry in the 19th century. 

Henry's Law Formula

As we know, Henry's law is the amount of gas dissolved in the liquid is directly proportional to the partial pressure of the gas above the liquid at equilibrium. The mathematical formula of Henry's Law is written as-

P ∝ C 

P = Kh. C

Where, 

P indicates the partial pressure of the gas above the liquid

Kh indicates the proportionality constant

C indicates the amount of dissolved gas

Factor Affecting Henry's Law Constant

The factors that affect the Henry law constant are-

• Nature of gas
• Nature of Solvent
• Pressure
• Temperature

Limitations of Henry’s Law

Some of the limitations of Henry's Law are-

• Only applicable when the molecules are in the state of equilibrium.
• This law is only applicable when the pressure of the system is not so high.
• Applicable to those gases which do not react or do not participate in a chemical reaction.

Application of Henry’s Law

The application of Henry's Law is-

• For increasing the solubility of CO2 in soft drinks and soda water.
• Production of carbonated beverages.
• Deep-sea diving.
• It helps scuba drivers to breathe deep inside the earth.
• Also, it helps climbers at high altitudes preventing them from anoxia.