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
Notes
Sulfuric acid
H2SO4
+6
Sulfate, SO2− 4 and hydrogen sulfate commonly known as bisulfate, HSO− 4
Best known and industrially significant.
Polysulfuric acids including disulfuric acid (pyrosulfuric acid)
H2SO4·nSO3
+6
Disulfate (commonly known as pyrosulfate), S 2O2− 7 and trisulfate, S 3O2− 10
Pure disulfuric acid melts at 36 °C. Present in fuming sulfuric acid, oleum. Examples known for n = 1 and n = 2.
Peroxymonosulfuric acid
H2SO5
+6
Peroxomonosulfate, OOSO2− 3
"Caro's acid", a solid melting at 45 °C
Peroxydisulfuric acid
H2S2O8
+6
Peroxydisulfate, O 3SOOSO2− 3
"Marshall's acid", a solid melting at 65 °C.
Dithionic acid
H2S2O6
+5
Dithionate, O 3SSO2− 3
Not isolated in pure form, only concentrated solutions have been prepared
Thiosulfuric acid
H2S2O3
0 (for the terminal sulfur), +4 (for the central atom)
Thiosulfate, S 2O2− 3 Hydrogenthiosulfate HS 2O− 3 (ammonium salt prepared in anhydrous methanol at −80 °C[1])
Aqueous solutions decompose.
Disulfurous acid or pyrosulfurous acid
H2S2O5
+5 (of the sulfur atom bonded to 3 oxygen atoms), +3 (of other sulfur atom)
Disulfite commonly known as metabisulfite, S 2O2− 5
Not known.
Sulfurous acid
H2SO3
+4
Bisulfite, HSO− 3 and sulfite, SO2− 3
Not known.
Dithionous acid
H2S2O4
+3
Dithionite, O 2SSO2− 2
Not known.
Sulfoxylic acid
H2SO2
+2
Sulfoxylate, SO2− 2
Free acid not known
Polythionic acid
H2SxO6
0 (for the bridging S atoms), +5 (for the terminal central S atoms)
Polythionates, O 3S(S x−2)SO2− 3. 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 acid
H2S2O2
−1 (for the exterior sulfur atom ), +3 (for the central atom)
Thiosulfites
Not known
Dihydroxydisulfane
H2S2O2
+1
Acid known
^Raman spectroscopic discovery of the hydrogenthiosulphate anion, HSSO− 3, in solid NH4HS2O3 Steudel Rr.; Prenzel A Zeitschrift für Naturforschung 1989,44, 12, 1499-1502
Sulfuroxoacids are chemical compounds that contain sulfur, oxygen, and hydrogen. The best known and most important industrially used is sulfuric acid...
ether – also known as "sweet oil of vitriol" Piranha solution SulfuroxoacidSulfuric acid poisoning Haynes, William M. (2014). CRC Handbook of Chemistry...
pyrosulphuric acid), also named oleum, is a sulfuroxoacid. It is a major constituent of fuming sulfuric acid, oleum, and this is how most chemists encounter...
meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more...
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one...
acid (H2SO2) (also known as hyposulfurous acid or sulfur dihydroxide) is an unstable oxoacid of sulfur in an intermediate oxidation state between hydrogen...
Peroxymonosulfuric acid, H 2SO 5, is also known as persulfuric acid, peroxysulfuric acid, or Caro's acid. In this acid, the S(VI) center adopts its characteristic...
Sulfuric(IV) acid (United Kingdom spelling: sulphuric(IV) acid), also known as sulfurous (UK: sulphurous) acid and thionic acid,[citation needed] is the...
chloride with a solution of sulfur trioxide in sulfuric acid: HCl + SO3 → ClSO3H It can also be prepared by chlorination of sulfuric acid, written here for...
commercially available. It is a tetrahedral molecule and is closely related to sulfuric acid, H2SO4, substituting a fluorine atom for one of the hydroxyl groups...
Dithionous acid is a sulfuroxoacid with the chemical formula H2S2O4. It is unstable in pure form, but its salts, known as dithionites, are stable. It...
Silica sulfuric acid (SiO 2-OSO 3H 2, SSA), a solid acid, is prepared by soaking silica gel with sulfuric acid. SSA is used as a catalyst in different...
Polythionic acid is an oxoacid which has a straight chain of sulfur atoms and has the chemical formula Sn(SO3H)2 (n > 2). Trithionic acid (H2S3O6), tetrathionic...
Marshall, who discovered it in 1891. This oxoacid features sulfur in its +6 oxidation state and a peroxide group. Sulfur adopts the usual tetrahedral geometry...
Disulfurous acid, metabisulfurous acid or pyrosulfurous acid is an oxoacid of sulfur with the formula H2S2O5. Its structure is HO−S(=O)2−S(=O)−OH. The...
Piranha solution, also known as piranha etch, is a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). The resulting mixture is used to clean...
to water, sulfur trioxide, sulfur dioxide and nitrogen. Sulfamic acid (H3NSO3) may be considered an intermediate compound between sulfuric acid (H2SO4)...
water. The decomposition products can include sulfur, sulfur dioxide, hydrogen sulfide, polysulfanes, sulfuric acid and polythionates, depending on the reaction...
part of the lead chamber process for producing sulfuric acid. The compound is the mixed anhydride of sulfuric acid and nitrous acid. In organic chemistry...
methods entail reaction of primary amines with sources of sulfur trioxide such as pyridine-sulfur trioxide: RNH2 + SO3 → RNHSO3H Sulfamation can also be...
hypodithionous acid is a reduced sulfur oxyacid with sulfur in a formal oxidation state of +1, but the valence of sulfur is 2. The structural formula is...
to calculations. The sulfur analog of thiosulfuric acid (HS−S(=O)2−OH), in which two sulfur atoms branch off of the central sulfur atom of a linear dihydrogen...
a larger scale they are made by oxidizing a cooled aqueous solution of sulfur dioxide with manganese dioxide: 2 MnO2 + 3 SO2 → MnS2O6 + MnSO4 The manganese...
Chloric acid, HClO3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid (pKa ≈ −2.7) and an oxidizing agent. Chloric...
Sulfinic acids are oxoacids of sulfur with the structure RSO(OH). In these organosulfur compounds, sulfur is pyramidal. Sulfinic acids RSO2H are about...
(also known as an acid halide) is a chemical compound derived from an oxoacid by replacing a hydroxyl group (−OH) with a halide group (−X, where X is...
and the most stable of the nitrogen oxoacids. It is one of the three most used acids (the other two being sulfuric acid and hydrochloric acid) and was...
acid is a polythionic acid with three sulfur atoms. It can be viewed as two bisulfite radicals bridged by a sulfur atom. EBI Web Team. "trithionic acid...
manganic(VII) acid) is the inorganic compound with the formula HMnO4. This strong oxoacid has been isolated as its dihydrate. It is the conjugate acid of permanganate...
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