Chemical elements
  Potassium
    Isotopes
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    Physical Properties
    Chemical Properties
      Potassium hydride
      Potassium fluoride
      Potassium hydrogen fluoride
      Potassium chloride
      Potassium bromide
      Potassium iodide
      Potassium hypochlorite
      Potassium chlorate
      Potassium perchlorate
      Potassium hypobromite
      Potassium bromate
      Potassium perbromate
      Potassium hypoiodite
      Potassium iodate
      Potassium periodate
      Potassium monoxide
      Potassium peroxides
      Potassium hydroxide
      Potassium monosulphide
      Potassium sulphide
      Potassium polysulphides
      Potassium hydrogen sulphide
      Potassium sulphite
      Potassium hydrogen sulphite
      Potassium pyrosulphite
      Potassium sulphate
      Potassium hydrogen sulphate
      Potassium pyrosulphate
      Potassium persulphate
      Potassium thiosulphate
      Potassium dithionate
      Potassium trithionate
      Potassium tetrathionate
      Potassium pentathionate
      Potassium hyposulphite
      Potassium selenides
      Potassium selenate
      Potassium tellurides
      Potassium tellurate
      Potassium nitride
      Potassium hydrazoate
      Potassamide
      Potassium hyponitrite
      Potassium nitrite
      Potassium nitrate
      Potassium phosphides
      Potassium hypophosphite
      Potassium orthophosphates
      Potassium pyrophosphate
      Potassium metaphosphate
      Potassium arsenite
      Potassium arsenates
      Potassium carbide
      Potassium carbonate
      Potassium sodium carbonate
      Potassium bicarbonate
      Potassium hydrogen carbonate
      Potassium percarbonate
      Potassium thiocarbonate
      Potassium cyanide
      Potassium thiocyanate
      Potassium silicates
      Potassium fluosilicate
      Potassium silicofluoride
      Potassium hypoborate
      Potassium borates
      Dipotassium tetraborate
      Potassium perborates
      Potassium oxalate
    PDB 1a3w-1dul
    PDB 1dz4-1j95
    PDB 1jbr-1lqp
    PDB 1lrt-1o07
    PDB 1o76-1qb9
    PDB 1qj5-1t86
    PDB 1t87-1vq9
    PDB 1vqk-1yj9
    PDB 1yjn-2aop
    PDB 2apo-2f4v
    PDB 2fbw-2hg9
    PDB 2hh1-2oij
    PDB 2oiy-2uxb
    PDB 2uxc-2x20
    PDB 2x21-3c0y
    PDB 3c0z-3dix
    PDB 3diy-3f5w
    PDB 3f7j-3hqo
    PDB 3hqp-3l01
    PDB 3l0u-3oi5
    PDB 3oia-3r9b
    PDB 3rde-4e6k
    PDB 4edj-8gep

Potassium polysulphides






Several polysulphides have been described. According to Thomas and Rule, the complete series K2SX exists, x being any whole number up to a maximum of 6. The values obtained for the molecular weights in alcoholic solution by the ebullioscopic method favour the simple formula K2Sx., and not K4Sx.


Potassium trisulphide, K2S3

The trisulphide, K2S3, is formed by the action of excess of sulphur on a solution of potassium in liquid ammonia. The tetrasulphide, K2S4, the most stable member of the series, can be prepared by heating a mixture of potassium carbonate and sulphur at 800° C. in a current of carbon dioxide, or by the action of hydrogen sulphide on the fused pentasulphide. It yields an octahydrate, a trihydrate, and a semihydrate. Its heat of formation from the elements is 116.6 Cal.

Potassium pentasulphide, K2S5

The pentasulphide, K2S5, is formed at lower temperatures from the carbonate by the action of excess of sulphur, thiosulphate being also produced by heating the two substances in a closed vessel at 250° C., the mixture constituting one variety of the so-called " liver of sulphur." A better method for preparing the pentasulphide is to saturate a solution of potassium ethoxide with hydrogen sulphide and add the equivalent amount of sulphur. By this process it has not been found possible to prepare the disulphide, trisulphide, tetrasulphide, or hexasulphide, even when the calculated proportions of the materials are employed, the product being invariably the pentasulphide. Thus prepared, the substance forms an orange-red, very hygroscopic, crystalline solid. At 220° C. it melts with decomposition. When in contact with air, or in aqueous solution, it undergoes gradual decomposition, with liberation of sulphur.

Potassium Polysulphides K4S5 and K4S8

Polysulphides of the formulae K4S5 and K4S8 have also been prepared by the interaction of the solid primary sulphide with hydrogen sulphide. Aqueous solutions of the monosulphide are unsuited for preparing individual polysulphides.
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