{"term":{"id":"15358","title":"Sieverts’ law","longtitle":"IUPAC Gold Book - Sieverts’ law","doi":"10.1351\/goldbook.15358","code":"15358","status":"current","definitions":[{"id":1,"text":"Solubility of a diatomic gas in a molten metal is proportional to the square root of the partial pressure.","notes":{"1":"The law follows from the solubility constant for equilibrium dissolution of an ideal diatomic gas \\(\\ce{X2}\\) in a metal \\(\\ce{M}\\) to form an ideal solution of dissociated atoms: \\[\\ce{X2(g)  2X(M)}\\] for which, and for dilute solutions of the gas, \\[K_{{\\rm{s}},x} = a(\\ce{X},\\ce{M})^{2}\/a(\\ce{X2},{\\rm{g}}) \\approx x(\\ce{X},\\ce{M})^{2} p^{_{^⦵\\!}}\/p (\\ce{X2},\\rm{g})\\] where \\(x(\\ce{X},\\ce{M})\\) is the solubility of the gas in the molten metal expressed as a mole fraction of \\(\\ce{H\\mbox{-}atoms}\\). The solubility constant \\(K_{\\rm{s},x}\\) is called the Sieverts constant.","2":"Other forms of the solubility constant are common, especially in terms of amount concentrations or mass fractions (especially in metallurgical papers) instead of mole fractions."},"links":[{"term":"solubility constant","url":"https:\/\/goldbook.iupac.org\/terms\/view\/15359"}],"sources":["PAC, 2008, 80, 233. 'Glossary of terms related to solubility (IUPAC Recommendations 2008)' on page 263 (https:\/\/doi.org\/10.1351\/pac200880020233)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/15358\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/15358\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/15358\/plain"},"citation":"Citation: 'Sieverts’ law' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.15358","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-06-28T17:15:39+00:00"}}