Chemical elements
  Potassium
    Isotopes
    Energy
    Preparation
    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 chloride, KCl






The Potassium chloride, KCl is found in nature as sylvine: in combination as carnallite, KCl,MgCl2,6H2O; kainite, KCl,MgSO4,3H2O; and as douglasite, K2FeCl4,2H2O. It is also a constituent of the ashes of plants, and of the residues from the manufacture of alcohol from beet-molasses.

Potassium chloride can be synthesized from potassium and chlorine, the elements combining directly under the influence of heat, or at ordinary temperature in presence of moisture. At - 80° C. the metal does not combine with chlorine. The salt can be prepared by the action of hydrochloric acid on the carbonate.

In addition to kainite and sylvine, the salt deposits at Stassfurt ("Abraumsalze") contain 55 to 65 per cent, of carnallite, associated with 20 to 25 per cent, of rock-salt, 10 to 20 per cent, of kieserite, MgSO4,H2O, and 2 to 4 per cent, of tachydrite, CaCl2,2MgCl2,12H2O. The technical preparation of potassium chloride from these deposits depends on the ready solubility of carnallite, and the crystallization of potassium chloride from hot saturated solutions of this substance. Kainite is employed as a source of potassium chloride, and the compound is also obtained by fractional crystallization of the salts present in sea-water and in the ash of seaweed.

A process for the production of potassium chloride from orthoclase was patented by Bassett, but has not been worked technically. It was discovered independently and investigated by Ashcroft, and consists in heating finely divided orthoclase with sodium chloride in equal proportion by weight at 900° to 1000° C., 85 per cent, of the potassium in the mineral being replaced by sodium in accordance with the scheme

K2O,Al2O3,6SiO2 + 2NaClNa2O,Al2O3,6SiO2 + 2KCl.

The potassium chloride can be separated from the insoluble sodium felspar by lixiviation, and from the excess of sodium chloride by fractional crystallization. This process might afford a new method for the manufacture of potassium chloride. It has also been found possible to extract the salt from the dust of the blast-furnace.

Potassium chloride forms colourless cubes, and has also been obtained in octahedra, rhombododecahedra, and icositetrahedra. Its melting-point is given as 762° C., 772.3° C., 774° C., 775° C., 778° C., and 790° C. It volatilizes without decomposition, the molecular weight derived from the vapour density, and also that from the depression of the freezing-point of mercuric chloride,12 corresponding with the simple formula KCl. For the density are given the mean value 1.977, and also 1.989 at 16° C., 1.991 at 20° C., 1.994 at 20.4° C., 1.951 at 23.4° C., 1.612 at the melting-point. The specific heat is given as 0.171 between 13° and 46° C., 0.1730 between 14° and 99° C., 0.1840 between 20° and 726° C., and for the fused salt 0.2671 between 807° and 935° C. The latent heat of fusion per gram is recorded as 0.063 Cal. And 0.086 Cal. At 801° C. the vapour-pressure is 1.54 mm.; at 948° C. it is 8.33 mm.; and at 1044° C. it is 24.1 mm. The molecular electric conductivity between 775.7° and 943.5° C. is given by the formula

μt = 115.4 + 0.2575(t - 800).

The heat of formation from the elements is given as 105.6 Cal. and 105.7 Cal.

Solubility of Potassium chloride in water

Temperature. °C.051015202530405060708090100130147180
Solubility in 100 grams of water27.629.331.032.434.035.537.040.042.645.548.351.154.056.766.070.877.5


The boiling-point of the saturated solution in contact with excess of the salt is 108.6° C. at 760 mm.

At 25° C. 100 grams of ethyl alcohol dissolve 0.022 gram of potassium chloride.

Double chlorides of potassium and other metals have also been prepared. Potassium chloride does not form either compounds or mixed crystals with lithium chloride.


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