Henry's Law Constants (Solubilities)


Table of contents

1) Introduction

Calculations in atmospheric chemistry depend strongly on the availability of kinetic and thermodynamic data. For gas-phase chemistry, evaluations such as the IUPAC or JPL data sets greatly facilitate obtaining reliable values. However, there has been no such comprehensive compilation for Henry's law constants (solubilities) for tropospheric modeling of clouds and aerosol particles. Waste water treatment is another research area where Henry's law constants are needed since solubility affects volatilization of toxic compounds into the air. I have gathered data from different sources. The Henry's law constants kH, which can (unfortunately) be defined in several ways and expressed using different units, have been converted into a uniform format (unit: mol dm-3 atm-1). The current version contains about 2200 data entries for more than 900 species collected from over 250 references. The printed document contains 107 pages.

2) Download and copyright

The list is available here as a pdf file. It can be printed or used to search the document electronically: henry.pdf

Before using the data, please read also the Errata section!

You can download the list of Henry's law constants for non-commercial use under the Creative Commons Attribution - NonCommercial - ShareAlike Licence

3) Converting Henry's Law Constants

Here, I use the following name conventions for Henry's law constants:

kH = Henry's law constants representing solubility (i.e. aqueous-phase composition divided by gas-phase composition)

kH,inv = Henry's law constants representing volatility (i.e. gas-phase composition divided by aqueous-phase composition)

Additional superscripts denote which properties are used:

symbol definition description unit(s)
kHcp c/p aq-concentration / partial pressure [mol/(m3*Pa)] or [M/atm]
kHcc c/c aq-concentration / gas-concentration dimensionless
kHbp b/p molality / partial pressure [mol/(kg*Pa)] or [mol/(kg*atm)]
kHxp x/p molar fraction / partial pressure [1/atm]
kH,invpx p/x partial pressure / molar fraction [atm]
kH,invpc p/c partial pressure / aq-concentration [m3*Pa/mol]
kH,invcc c/c gas-concentration / aq-concentration dimensionless

Table I: Conversion factors between several Henry's law constants kH representing solubility (at T=298.15 K and rho=997 kg/m3).

  kHcp = ... mol/(m3Pa) kHcp = ... M/atm kHcc = ... (dim.-less aq/g) kHbp = ... mol/(kg Pa)
kHcp = 1 mol/(m3Pa) 1 1.013E+02 2.479E+03 1.003E-03
kHcp = 1 M/atm 9.869E-03 1 2.446E+01 9.899E-06
kHcc = 1 (dim.-less aq/g) 4.034E-04 4.088E-02 1 4.046E-07
kHbp = 1 mol/(kg Pa) 9.970E+02 1.010E+05 2.471E+06 1

Table II: Conversion factors between several inverse Henry's law constants kH,inv representing volatility (at T=298.15 K and rho=997 kg/m3).

  kH,invpx = ... atm kH,invpc = ... m3Pa/mol kH,invcc = ... (dim.-less g/aq)
kH,invpx = 1 atm 1 1.831E+00 7.386E-04
kH,invpc = 1 m3Pa/mol 5.462E-01 1 4.034E-04
kH,invcc = 1 (dim.-less g/aq) 1.354E+03 2.479E+03 1

Table III: Products of Henry's law constants kH representing solubility and inverse Henry's law constants kH,inv representing volatility (at T=298.15 K and rho=997 kg/m3).

  kHcp kHcp kHcc kHbp
  [mol/(m3Pa)] [M/atm] (dim.-less aq/g) [mol/(kg Pa)]
kH,invpx [atm] 5.462E-01 5.534E+01 1.354E+03 5.478E-04
kH,invpc [m3Pa/mol] 1 1.013E+02 2.479E+03 1.003E-03
kH,invcc (dim.-less g/aq) 4.034E-04 4.088E-02 1 4.046E-07

4) Frequently asked questions

What kind of data is included in the list?

The list contains Henry's law constants for several organic and inorganic species in water. The Henry's law constant is defined here as the ratio of the aqueous-phase concentration of a chemical to its equilibrium partial pressure in the gas phase.

What kind of data is NOT included in the list?

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.

Why are CO and CO2 apparently not included?

You cannot find them in the inorganic section. CO and CO2 are included in the miscellaneous organics subsection (all species containing carbon atoms are in the organic section).

Will this list be published in a refereed journal?

For now I have decided to have the list only on the web. I consider this as a "public reviewing process". Since I put the list on the web, I have been told about several additional references and some minor errors have been pointed out to me. Eventually, however, I will submit it to a refereed journal (probably Atmos. Chem. Phys.).

When is the next version of this list available?

At my current rate of productivity, you can expect a new version roughly every two years. Currently version 3 of the list is available. Work continues. I still have several articles that I want to include in the list. If you would like to be informed when version 4 is available, please send an email to rolf.sander@mpic.de.

How should I cite this work?

If you would like to cite this work, please cite it as:

R. Sander (1999)
Compilation of Henry's Law Constants for Inorganic and Organic Species of Potential Importance in Environmental Chemistry (Version 3)

Can you help me? I've got a question!

You're welcome to send me an email but please don't be too disappointed in case I don't have the time to answer it. Collecting Henry's law constants is not my main job. It's just something I did because I needed (and still need) them for my research. I have received much more email than I expected and I won't be able to answer all questions individually. Before sending me an email, please consider the following points:

Converting between different definitions and units for Henry's law constants can be quite tricky. I'm afraid I won't have the time to answer individual questions on how to convert from unit xxx to unit yyy.

Henry's law constants are used in several research areas, e.g. pesticide control, waste water management, and atmospheric chemistry. Since I'm an atmospheric chemist myself, I don't think I will be able to help you with problems in the other research areas.

5) Errata

Well, I knew it would happen... A big list like this just couldn't be perfect. I have now added a list of errors that I have made in my compilation.

Errata for version 3 (17 Feb 99)

6) Bug reports and comments

If you find errors in the list or if you know of additional references that I could include, please send me an email at rolf.sander@mpic.de. Especially when you have published measurements of Henry's law's constants, I would appreciate it very much if you send me a reprint! If you have any other comments or questions, please read the 'frequently asked questions' first (see above)!!!

7) Other sources of information

Rolf Sander This document was last changed 20 Sep 2013