Sulfur oxoacids are chemical compounds that contain sulfur, oxygen, and hydrogen. The best known and most important industrially used is sulfuric acid. Sulfur has several oxoacids; however, some of these are known only from their salts (these are shown in italics in the table below). The acids that have been characterised contain a variety of structural features, for example: tetrahedral sulfur when coordinated to oxygen terminal and bridging oxygen atoms terminal peroxo groups terminal S=S chains of (−S−)n
Acid Formula Formal oxidation number Structure Related anions NotesSulfuric acidH2SO4 +6Sulfate, and hydrogen sulfate commonly known as bisulfate, Best known and industrially significant.Polysulfuric acids including disulfuric acid (pyrosulfuric acid)H2SO4·nSO3 +6Disulfate (commonly known as pyrosulfate), and trisulfate, Pure disulfuric acid melts at 36 °C. Present in fuming sulfuric acid, oleum. Examples known for n = 1 and n = 2.Peroxymonosulfuric acidH2SO5 +6Peroxomonosulfate, "Caro's acid", a solid melting at 45 °CPeroxydisulfuric acidH2S2O8 +6Peroxydisulfate, "Marshall's acid", a solid melting at 65 °C.Dithionic acid H2S2O6 +5Dithionate, Not isolated in pure form, only concentrated solutions have been preparedThiosulfuric acidH2S2O3 0 (for the terminal sulfur), +4 (for the central atom)Thiosulfate, Hydrogenthiosulfate (ammonium salt prepared in anhydrous methanol at −80 °CRaman spectroscopic discovery of the hydrogenthiosulphate anion, , in solid NH4HS2O3 Steudel Rr.; Prenzel A Zeitschrift für Naturforschung 1989,44, 12, 1499-1502)Aqueous solutions decompose.Disulfurous acid or pyrosulfurous acidH2S2O5 +5 (of the sulfur atom bonded to 3 oxygen atoms), +3 (of other sulfur atom)Disulfite commonly known as metabisulfite, Not known.Sulfurous acid H2SO3 +4Bisulfite, and sulfite, Not known.Dithionous acidH2S2O4 +3Dithionite, Not known.Sulfoxylic acidH2SO2 +2Sulfoxylate, Free acid not knownPolythionic acidH2SxO6 0 (for the bridging S atoms), +5 (for the terminal central S atoms)Polythionates, . Example trithionate, tetrathionate, pentathionate, hexathionate, heptathionate, octathionate, nonathionate, decathionate, undecathionate, dodecathionate, tridecathionate, and tetradecathionate.Examples known with x = 3, 4, 5, 6, 7, 8, 10, 12, 14.Thiosulfurous acidH2S2O2 −1 (for the exterior sulfur atom ), +3 (for the central atom)ThiosulfitesNot knownDihydroxydisulfaneH2S2O2 +1Acid known
See also Chlorosulfuric acid Fluorosulfuric acid Nitrosylsulfuric acid Peroxydisulfuric acid Sulfinic acids Sulfonic acids
References
External links Sulfur oxoacids along with other acids containing sulfur