Document Download: R11-24: Revised Release on the Ionization Constant of H2O

Description

This formulation is recommended for the calculation of the ionization constant of ordinary water as a function of temperature and density. The range of validity is from 0 to 1000 °C at pressures up to 1000 MPa. 
The original development of the formulation is described in detail in a scientific article. A more recent article describes the 2024 revision in which improved parameters for the formulation were presented.

Revision History

• This Release was adopted by IAPWS in 2007, replacing an earlier release from 1980.
• In 2019, a minor revision was made to correct some of the explanatory text and to update some references; the formulation itself was not changed.
• In 2024, a major revision was performed in which the parameters of the 2007 formulation were re-adjusted to better describe newly derived experimental data at near-critical and supercritical conditions.

This Release is the product of the Working Group "Thermophysical Properties of Water and Steam" (TPWS) of the International Association for the Properties of Water and Steam (IAPWS).