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# Henry's law

Henry's law states that the mass of a gas that dissolves in a definite volume of liquid is directly proportional to the pressure of the gas provided the gas does not react with the solvent. William Henry[?] formulated the formula in 1801.

A formula for Henry's Law is:

[itex] e^P = e^{kC} [/itex]

where P is the partial pressure of the gaseous solute above the solution, C is the concentration of the gas in mol/L and k is the Henry's Law constant[?], which has the units L*atm/mol.

Taking the natural logarithm of the formula, gives us the more commonly used formula:

[itex] P = kC [/itex]

This version is used to showcase the effectiveness of the law for dilute solutions of gases that don't react with the solvent. Some values for k include:

• O2 : 4.34×104 atoms
• CO2 : 1.64×103 atoms
• H2 : 7.04×104 atoms

when these gases are dissolved in water at 299 Kelvins

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