Chemical elements
  Selenium
    Isotopes
    Energy
    Production
    Application
    Allotropy
    Colloidal
    Physical Properties
    Chemical Properties
      Hydrogen Selenide
      Selenium Fluorides
      Selenium Monochloride
      Selenium Tetrachloride
      Selenium Monobromide
      Selenium Tetrabromide
      Selenium Chlorobromides
      Selenium Oxyfluoride
      Selenium Oxychloride
      Sulphur Selenium Oxytetrachloride
      Selenium Oxybromide
      Chloroselenic Acid
      Selenium Dioxide
      Selenious Acid
      Selenium Trioxide
      Selenic Acid
      Selenates
      Perselenic Acid
      Selenium Sulphoxide
      Selenotrithionic Acid
      Diselenotrithionic Acid
      Selenopentathionic Acid
      Selenium Nitride
      Nitrosylselenic Acid
      Phosphorus Subselenide
      Phosphorus Monoselenide
      Tetraphosphorus Triselenide
      Phosphorus Triselenide
      Phosphorus Pentaselenide
      Phosphorus Chloroselenide
      Selenophosphates and Oxyselenophosphates
      Carbon Diselenide
      Carbon Subselenides
      Carbon Oxyselenide
      Carbon Sulphidoselenide
      Cyanogen Monoselenide
      Cyanogen Diselenide or Selenocyanogen
      Cyanogen Triselenide
      Selenocyanic Acid
      Ammonium Selenocyanate
      Caesium Triselenocyanate
      Copper Selenocyanate
      Lead Selenocyanate
      Magnesium Selenocyanate
      Mercurous Selenocyanate
      Mercuric Selenocyanate
      Potassium Selenocyanate
      Silver Selenocyanate
      Sodium Selenocyanate
      Zinc Selenocyanate
      Silicon Selenide
    Detection and Estimation

Potassium Selenocyanate, KCNSe






Berzelius prepared Potassium Selenocyanate, KCNSe, by the action of selenium on potassium ferrocyanide:

K4Fe(CN)6 + 4Se = 4KCNSe + FeC2 + N2.

By fusing pure potassium cyanide with selenium, Muthmann and Schroder obtained potassium selenocyanate satisfactorily.

The salt crystallises in very deliquescent needles. The action of chlorine on its solution is complex, intermediate compounds being formed; the solution becomes dark red, some selenium is precipitated, and cyanogen triselenide is finally formed. The main reaction may probably be expressed by the equation:

16KCNSe + 7Cl2 + 3H2O = 5Se3(CN)2 + K2SeO3 + 6HCN + 14KCl.

Iodine reacts with potassium selenocyanate in solution in the presence of much sodium bicarbonate according to the following equation:

KCNSe + 6I + 3H2O = H2SeO3 + KI + 4HI + ICN.

By using excess of iodine and titrating after one hour with sodium thiosulphate in the presence of a little carbon disulphide, the reaction may be used for the determination of the selenocyanate.

A double selenocyanate of potassium and platinum may be obtained by mixing alcohol solutions of potassium selenocyanate and either platinum tetrachloride or chloroplatinic acid. The double salt, potassium platiselenocyanate, K2Pt(CNSe)6, consists of hexagonal plates, density 3.377 at 10.2° C., dark red by transmitted light and black by reflected light. The gold salt, KAu(CNSe)2, is obtained in a similar manner and consists of very easily decomposable dark red prisms.


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