Chemical elements
    Amorphous Sulphur
    Colloidal Sulphur
    Physical Properties
    Chemical Properties
      Hydrogen Sulphide
      Metal Polysulphides
      Hydrogen Polysulphides
      Hydrogen Pentasulphide
      Hydrogen Trisulphide
      Hydrogen Disulphide
      Sulphur Monofluoride
      Sulphur Tetrafluoride
      Sulphur Hexafluoride
      Sulphur Monochloride
      Sulphur Dichloride
      Sulphur Tetrachloride
      Sulphur Monobromide
      Thionyl Fluoride
      Sulphuryl Fluoride
      Fluorosulphonic Acid
      Thionyl Chloride
      Sulphuryl Chloride
      Sulphur Oxytetrachloride
      Pyrosulphuryl Chloride
      Chlorosulphonic Acid
      Thionyl Bromide
      Sodium Sulphoxylate
      Sulphur Dioxide
      Sulphurous Acid
      Sulphur Trioxide
      Pyrosulphuric Acid
      Sulphuric Acid
      Persulphuric Anhydride
      Persulphuric Acid or Perdisulphuric Acid
      Permonosulphuric Acid
      Amidopermonosulphuric Acid
      Thiosulphuric Acid
      Polythionic Acids
      Dithionic Acid
      Trithionic Acid
      Tetrathionic Acid
      Pentathionic Acid
      Wackenroders Solution
      Hexathionic Acid
      Polythionic Acids
      Sulphur Sesquioxide
      Hydrosulphurous Acid
      Nitrogen Sulphide
      Nitrogen Persulphide
      Nitrogen Pentasulphide
      Nitrogen Chlorosulphide
      Trithiazyl Chloride
      Thiotrithiazyl Chloride
      Dithiotetrathiazyl Chloride
      Nitrogen Bromosulphide
      Thiotrithiazyl Bromide
      Thiotrithiazyl Iodide
      Thiotrithiazyl Nitrate
      Thiotrithiazyl Hydrogen Sulphate
      Thiotrithiazyl Thiocyanate
      Sulphonic Acids
      Amidosulphonic Acid
      Imidosulphonic Acid
      Nitrilosulphonic Acid
      Hydroxylamine-monosulphonic Acid
      Nitrososulphonic Acid
      Hydroxylamine-disulphonic Acid
      Hydroxylamine-isodisulphonic Acid
      Hydroxylamine-trisulphonic Acid
      Dihydroxylamidosulphonic Acid
      Sulphazinic Acid
      Sulphazotinic Acid
      Dehydrosulphazotinic Acid
      Nitrosulphonic Acid
      Nitrosulphonyl Chloride
      Nitrosulphonic Anhydride
      Nitrosulphuric Acid
      Nitrosodisulphonic Acid
      Sulphonitronic Acid
      Sulphates of Hydroxylamine
      Hydroxylamine Dithionate
      Hydrazine Dithionate
      Hydrazine Amidosulphonate
      Carbon Subsulphide
      Carbon Monosulphide
      Carbon Disulphide
      Thiocarbonic Acid
      Ammonium thiocarbonate
      Thiolcarbonic Acid
      Xanthic Acid
      Perthiocarbonic Acid
      Sodium perthiocarbonate
      Carbonyl Sulphide
      Thiocarbonyl Chloride
      Thiocarbonyl Tetrachloride or
      Carbon Hexachlorosulphide
      Trichloromethyl Disulphide
      Thiocarbonyl Sulphochloride
      Carbon Bromosulphide
      Amino-derivatives of Thiocarbonic Acid
      Dithiocarbamic Acid
      Azidodithiocarbonic Acid
      Cyanogen Monosulphide
      Cyanogen Trisulphide
      Sulphur Thiocyanate
      Disulphur Dithiocyanate
      Thiocyanic Acid
      Dithiocyanic Acid
      Trithiocyanuric Acid
      Perthiocyanic Acid

Fluorosulphonic Acid, FSO2(OH)

Fluorosulphonic Acid, FSO2(OH), was first obtained by the addition of anhydrous hydrogen fluoride to sulphur trioxide in a platinum vessel cooled in a freezing mixture, a slight excess of the halogen acid being used and removed subsequently by a current of dry carbon dioxide at about 30° C.:

SO3 + HF = (OH).SO2F.

It is more conveniently prepared by dissolving ammonium fluoride in fuming sulphuric acid and heating, when fluorosulphonic acid distils; 3 metallic fluorides may also be used.

Fluorosulphonic acid is a mobile, colourless liquid, boiling at 162.6° C.; it possesses only a slight pungent odour, and has little-action on the dry skin. Distillation is accompanied by only very slight decomposition, probably into sulphuryl fluoride and sulphuric acid. Water causes vigorous decomposition; dry glass is but slightly affected; lead is rapidly converted into lead sulphate and fluoride, whilst with sulphur, sulphur dioxide and hydrofluoric acid are slowly produced.


The alkali fluorosulphonates may be prepared by the action of the corresponding hydroxides upon an aqueous solution of ammonium fluorosulphonate. Ammonium fluorosulphonate is best obtained by the gradual addition of dry ammonium fluoride to sulphuric acid containing about 70 per cent. SO3, the product being treated with a slight excess of ammonia dissolved in methyl alcohol. Fluorosulphonates can also be obtained by heating together pyrosulphates and fluorides, either in the dry state or in the presence of a little water. Double decomposition may also be effected between fluorosulphonic acid and sodium chloride at 230° C. with formation of sodium fluorosulphonate. Ammonium fluorosulphonate melts at 245° C., and reacts readily with gaseous ammonia, particularly at low temperatures, forming liquid ammines. Potassium fluorosulphonate melts at 311° C., and the rubidium salt at 304° C. The lithium salt forms long, shining needles, which contain three molecules of water of crystallisation, and melt at 60° to 61° C. In the anhydrous state the lithium salt melts at about 360° C.

The fluorosulphonates are stable towards water and may be crystallised from this solvent. In the presence of mineral acids they are readily hydrolysed to hydrofluoric and sulphuric acids. In alkaline solution they are much more stable. They interact with ammonium hydroxide, forming chiefly aminosulphonates. The alkali fluorosulphonates are very stable towards heat.
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