Chemical elements
    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
      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 nitrite, KNO2

The Potassium nitrite, KNO2, is made by the reduction of potassium nitrate by heating it alone, or with metals such as lead and iron, or with substances containing sulphur or carbon. It is also formed from potassium nitrate by electrolysis with a silver cathode and a copper anode, the yield being almost quantitative. The pure salt can be obtained by precipitating the aqueous solution with methyl alcohol. Another method for the production of the nitrite depends on the double decomposition of silver nitrite and lithium chloride.

The pure, anhydrous nitrite is not hygroscopic, but as usually prepared the substance is a very deliquescent, crystalline solid, its aqueous solution having a slight alkaline reaction. At 15.5° C. the solubility is 300 grams per 100 grams of water. The heat of formation in aqueous solution from the elements is 88.9 Cal. The products of electrolytic reduction are hyponitrite, ammonia, and hydroxylamine.

At 350° C. potassium nitrite begins to decompose in accordance with the equations

3KNO2 = K2O + KNO3 + 2NO;
5KNO2 = K2O + 3KNO3 + 2N.

Heating with nitrogen peroxide oxidizes the nitrite to nitrate:

KNO2 + NO2 = KNO3 + NO.

Potassium nitrite readily reacts with cold sulphuric acid of 17 per cent, strength, yielding a mixture of nitric oxide and higher oxides of nitrogen. If the mixed gases are passed through a solution of an alkali-metal hydroxide, pure nitric oxide is isolated. For laboratory purposes this method affords a convenient means of preparing the gas, 10 grams of potassium nitrite producing about 2.5 litres of the oxide.

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