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 Oxalate, K2C2O4,H2O






Oxalic acid forms with potassium not only the two salts which, according to the dibasic nature of the acid, are to be expected, but also another salt which can be regarded as a compound of oxalic acid with acid potassium oxalate. Of the salts of oxalic acid, those with potassium are the best known, because they occur in the juices of various plants, from which they were early prepared, and have led to the knowledge of oxalic acid.

Normal potassium oxalate, K2C2O4,H2O, is a white salt soluble in water, and is used in photography.

Acid potassium oxalate

Acid potassium oxalate, KHC2O4 + 1H2O, is called salt of sorrel, because it was first obtained by evaporation and crystallisation from the juice of the wood-sorrel. It is less soluble than the normal salt, and is used for removing iron and ink stains, since it converts iron salts into soluble (complex) compounds.

Potassium tetroxalate

Potassium tetroxalate is the name given to the salt KHC2O4. H2C2O4 + 2H2O, which is easily obtained by mixing one of the previous salts with the necessary excess (or rather more) of oxalic acid in warm, concentrated solution. It then quickly crystallises out, since it is rather sparingly soluble. This salt is used in volumetric analysis in place of free oxalic acid, because it does not effloresce so readily as the latter, and allows therefore of definite amounts being accurately weighed out.

If two equal amounts of acid potassium oxalate are weighed out, and one converted, by heating, into potassium carbonate and then dissolved along with the second portion, a liquid having a perfectly neutral reaction is obtained, after the carbonic acid is boiled off. This is a proof that in the acid oxalate exactly half as much potassium is contained as is necessary for the preparation of the normal salt. In this simple manner, the law of multiple proportions was proved by Wollaston as early as the year 1808.


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