Converting Henry's Law Constants

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

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

kH,inv = Henry's law coefficients 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

You can convert Henry's law constants here:

=
The conversions are performed using the factors from the tables below. More information is available from my review article "Modeling atmospheric chemistry: Interactions between gas-phase species and liquid cloud/aerosol particles" in Surv. Geophys., 20, 1-31 (1999).

Table I

Conversion factors between several Henry's law coefficients 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 coefficients 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 coefficients kH representing solubility and inverse Henry's law coefficients 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
Another on-line converter is available here.
Rolf Sander This document was last changed 23 May 2007