# Henry's Law Constants

### Rolf Sander

Atmospheric Chemistry Division

Max-Planck Institute for Chemistry
Mainz, Germany

## Errata

#### Contact, Imprint, Acknowledgements

When referring to the compilation of Henry's Law Constants, please cite this publication:

R. Sander: Compilation of Henry's law constants (version 4.0) for water as solvent, Atmos. Chem. Phys., 15, 4399-4981 (2015), doi:10.5194/acp-15-4399-2015

## Scientific background

Henry's law was formulated by the English chemist William Henry in the early 19th century. It states that the amount of dissolved gas is proportional to its partial pressure in the gas phase. The proportionality factor is called the Henry's law constant.

## The database

A compilation of 17350 Henry's law constants for 4632 organic and inorganic species in water was collected from 689 references by Sander (2015). Online access to the searchable database is available here.

## Symbols, definitions, and units

IUPAC recommends eight variants of Henry's law constants (Sander et al., 2022):

Here, the Henry's law solubility constant $Hscp$ is used. It is defined as the ratio of the aqueous-phase concentration of a chemical to its equilibrium partial pressure in the gas phase (at infinite dilution):

$Hscp = lim c→0 c/p$

To obtain other variants of the Henry's law constant, a conversion tool is available in the right column of this page.

## What kind of data is not included?

• Henry's law refers to small concentrations (lim c→0). Maximum solubilities are not included. Solubility products, i.e. products of ion concentrations are not included either.
• Henry's law constants for solvents other than water are not included.
• Values obtained under high pressures (p >> 1000 hPa) and temperatures (T > 373 K) are not included.

## Version History

Older (obsolete) versions of the compilation are also still available:
If you find errors or if you know of additional references that I could include, please send me an email at rolf.sander@mpic.de. If you have published measurements of Henry's law's constants, I would appreciate it very much if you send me a pdf of your paper!

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## Convert Henry's Law Constants

Convert: mol/(m3*Pa) (Hscp) M/atm (Hscp) 1/atm (Hsxp) mol/(kg*Pa) (Hsbp) mol/(kg*atm) (Hsbp) (dimensionless aq/g) (Hscc) m3*Pa/mol (Hvpc) m3*atm/mol (Hvpc) atm (Hvpx) (dimensionless g/aq) (Hvcc) (dimensionless aq/g) (alpha)