Henry’s-law constants of gases in water
Henry’s solubility constants at 25 °C and their temperature coefficients, with the 0 °C constants and air-saturated concentrations computed from them.
| Carbon dioxide | 0.034 | 2400 | 0.071 | 0.61 | |
|---|---|---|---|---|---|
| Argon | 0.0014 | 1300 | 0.0021 | 0.51 | |
| Oxygen | 0.0013 | 1700 | 0.0022 | 8.4 | |
| Nitrogen | 6.1 × 10⁻⁴ | 1300 | 9.1 × 10⁻⁴ | 13 | |
| Helium | 3.7 × 10⁻⁴ | 230 | 4.0 × 10⁻⁴ | 7.5 × 10⁻⁶ |
The 0 °C values use kH(T) = kH(298 K)·exp[C(1/T − 1/298.15)], assuming a constant enthalpy of solution, and may be a few per cent low. Air-saturated values subtract the 25 °C water vapour pressure (3.17 kPa); CO₂ is taken as 420 ppm.