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

Cyanogen Triselenide, Se3(CN)2






Cyanogen Triselenide, Se3(CN)2, may be prepared by the action of a current of chlorine diluted with air on an aqueous solution of potassium selenocyanate, KCNSe. It may also be advantageously obtained by the action of nitric oxide on a paste of potassium selenocyanate with water.

It crystallises from water in needles which melt at 132° C. and decompose at 148.5° C. From chloroform solution it crystallises in golden-yellow tabular crystals. Some selenium is deposited from its ether and alcohol solutions. It is soluble in benzene and in carbon disulphide.

When acted on by hot water, cyanogen triselenide reacts according to the equation:

2Se3(CN)2 + 2H2O = 5Se + SeO2 + 4HCN.

Calcium carbonate decomposes the triselenide thus:

2Se3(CN)2 + 3CaCO3 = 2Ca(CNSe)2 + CaSeO3 + Se + 3CO2.

The triselenide acts vigorously on many organic compounds with production of selenium, but the exact course of the reaction has not been ascertained in any one case as the products appear to be of a complex character.


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