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A thermodynamic rationalisation for the oxidising behaviour of concentrated H 2 SO 4
Author(s) -
Kish J. R.,
Ives M. B.
Publication year - 2011
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.20491
Subject(s) - chemistry , aqueous solution , sulfur , sulfuric acid , electrochemistry , pourbaix diagram , inorganic chemistry , electrolysis , hydrogen sulfide , chemical stability , organic chemistry , electrode , electrolyte
An attempt is made to extend the principle of equilibrium electrochemical potential–pH diagrams for sulfur compounds in dilute aqueous solutions of sulfuric acid (H 2 SO 4 ) to more concentrated aqueous solutions up to 100 wt.%. Published Hammett acidity data is used to account for the medium effect (undissociated H 2 SO 4 ) on the proton activity. The calculated electrochemical potential‐Hammett acidity diagrams predict a thermodynamic stability domain for all three of the reduction products experimentally observed during cathodic electrolysis, which included sulfur dioxide (SO 2 ), sulfur (S), and hydrogen sulfide (H 2 S). The implications of the relative stability domains on corrosion control measures are discussed.