Chemical elements
  Chromium
    Isotopes
    Energy
    Occurrence
    Preparation
    Physical Properties
    Chemical Properties
    Alloys
    Amalgams
    Compounds
      Chromous Fluoride
      Chromic Fluoride
      Chromyl Fluoride
      Chromous Chloride
      Chromic Chloride
      Oxychlorides
      Chromyl Chloride
      Trichromyl Chloride
      Chromium Chlorate
      Chromium Perchlorate
      Chromous Bromide
      Chromic Bromide
      Complex Halogen-halides
      Chromous Iodide
      Chromic Iodide
      Chromium Iodate
      Chromous Oxide
      Chromo-chromic Oxides
      Chromic Oxide
      Chromic Hydroxide
      Barium Chromite
      Cadmium Chromite
      Calcium Chromite
      Cobalt Chromite
      Cupric Chromite
      Cuprous Chromite
      Ferrous Chromite
      Lithium Chromite
      Magnesium Chromite
      Manganese Chromite
      Zinc Chromite
      Chromium Dioxide
      Chromium Trioxide
      Aluminium Chromate
      Ammonium Chromate
      Ammonium Lithium Chromate
      Ammonium Potassium Chromate
      Ammonium Sodium Chromate
      Ammonium Dichromate
      Ammonium Fluochromate
      Barium Chromate
      Barium Dichromate
      Barium Potassium Trichromate
      Beryllium Chromate
      Bismuth Chromate
      Bismuth Potassium Chromates
      Cadmium Chromate
      Cadmium Dichromate
      Cadmium Trichromate
      Caesium Chromate
      Caesium Dichromate
      Calcium Chromate
      Calcium Dichromate
      Cobalt Chromate
      Cobalt Dichromate
      Copper Chromates
      Cupric Dichromate
      Gold Chromates
      Iron Chromates
      Ferric Chromate
      Ferric Ammonium Chromate
      Lead Chromate
      Basic Lead Chromates
      Lead Dichromate
      Lithium Chromate
      Lithium Chlorochromate
      Magnesium Chromates
      Manganese Chromates
      Mercuric Chromate
      Mercuric Dichromate
      Nickel Chromate
      Nickel Dichromate
      Potassium Chromate
      Potassium Dichromate
      Potassium Trichromate
      Potassium Tetrachromate
      Potassium Fluochromate
      Potassium Chlorochromate
      Rubidium Dichromate
      Silver Chromate
      Silver Dichromate
      Sodium Chromate
      Sodium Dichromate
      Sodium Trichromate
      Sodium Chlorochromate
      Stannic Chromate
      Strontium Chromate
      Strontium Dichromate
      Strontium Trichromate
      Thallous Chromate
      Thallic Chromate
      Thallous Dichromate
      Thallous Trichromate
      Thallous Chlorochromate
      Uranyl Chromate
      Zinc Chromate
      Zinc Dichromate
      Zinc Trichromate
      Perchromic Acid
      Chromium Tetroxide Triammine
      Chromous Sulphide
      Chromium Tetrasulphide
      Chromic Sulphide
      Sodium Thiochromite
      Potassium Thiodichromite
      Chromic Sulphite
      Chromous Sulphate
      Chromic Sulphate
      Lithium Chromic Sulphate
      Sodium Chromic Sulphates
      Potassium Chromic Sulphates
      Potassium Chromium Alum
      Ammonium Chromium Alum
      Hydrazine Chromium Alum
      Sulphochromic Acid
      Chromous Selenide
      Chromic Selenide
      Chromic Selenite
      Chromium Nitrides
      Chromium Azide
      Chromic Nitrate
      Chromium Monophosphide
      Chromium Sesquiphosphide
      Chromic Hypophosphite
      Chromous Orthophosphate
      Chromic Orthophosphates
      Chromous Metaphosphate
      Chromic Metaphosphate
      Chromic Pyrophosphate
      Ammonium Chromi-pyrophosphate
      Potassium Chromi-pyrophosphate
      Sodium Chromi-pyrophosphate
      Chromous Thiophosphite
      Chromous Thiopyrophosphite
      Chromous Thiopyrophosphate
      Chromous Arsenide
      Chromium Sesqui-arsenide
      Chromic Arsenite
      Chromic Arsenate
      Chromium Pyroarsenate
      Chromic Thioarsenite
      Chromium Chlorantimonate
      Chromium Orthoantimonichloride
      Tetrachromium Carbide
      Pentachromium Dicarbide
      Tetrachromium Dicarbide
      Chromium Tungsten Carbide
      Chromous Carbonate
      Ammonium Chromous Carbonate
      Potassium Chromous Carbonate
      Sodium Chromous Carbonate
      Chromic Carbonates
      Chromium Thiocarbonate
      Chromous Cyanide
      Chromic Cyanide
      Potassium Chromocyanide
      Hydrogen Chromicyanide
      Ammonium Chromicyanide
      Lithium Chromicyanide
      Sodium Chromicyanide
      Potassium Chromicyanide
      Cobaltous Chromicyanide
      Cupric Chromicyanide
      Lead Chromicyanide
      Manganous Chromicyanide
      Mercury Chromicyanide
      Nickel Chromicyanide
      Silver Chromicyanide
      Zinc Chromicyanide
      Chromous Thiocyanate
      Chromic Thiocyanate
      Chromithiocyanic Acid
      Ammonium Chromithiocyanate
      Sodium Chromithiocyanate
      Potassium Chromithiocyanate
      Barium Chromithiocyanate
      Silver Chromithiocyanate
      Lead Chromithiocyanate
      Chromium Ferrocyanide
      Trichromium Silicide
      Dichromium Silicide
      Trichromium Disilicide
      Chromium Disilicide
      Chromium Aluminium Silicide
      Sodium Chromisilicates
      Chromium Silicofluoride
      Chromium Boride
      Trichromium Diboride
      Chromous Borate
      Chromic Borate
    Detection
    Estimation
    PDB 1huo-9icc

Manganese Chromates






The normal salts have not been isolated. When an alkali chromate is added to a solution of a manganese salt, some of the manganese undergoes oxidation, and the brownish-black precipitate formed, in addition to manganous and manganic chromates, is liable to contain manganate and permanganate, and trivalent chromium. If the reaction takes place in the cold, the alkali metal is found in the precipitate, but this can generally be removed at boiling temperature - most readily in the case of sodium.

The existence of most of the double salts which have been described in the literature must be considered as extremely doubtful, but by adding manganous chloride to a concentrated solution of potassium chromate, potassium manganese chromate, K2Mn(CrO4)2.2H2O, has been obtained by Groger as a red crystalline precipitate.

Mercury Chromates. - Mercurous chromate, Hg2CrO4, is obtained in the crystalline form as glittering red leaflets, when the amorphous precipitate produced by adding potassium dichromate to a solution of a mercurous salt is dissolved in boiling 5N nitric acid and the solution allowed to cool. It is also formed by adding potassium chromate to a solution of mercurous nitrate;4 the yellowish-brown amorphous precipitate first formed is unstable, and changes - without change of composition - into the crystalline form, the colour of which varies from yellow to bright red, depending on the fineness of the particles. The salt is not decomposed by water in the cold; it is converted by ammonia into the chromate of Millon's Base, (OHg2NH2)2CrO4. The formation of mercurous chromate affords a useful means of estimating chromium gravimetrically.

Basic salts have been described. By boiling the normal salt with water, or by treating the freshly formed amorphous precipitate with excess of mercurous nitrate solution, the salt, Hg6Cr2O9, or 2Hg2CrO4.Hg2O, results. If, during the gradual transition of the normal salt from the amorphous to the crystalline form, water is added so that hydrolysis occurs, the salt, Hg8Cr3O13, or 3Hg2CrO4.Hg2O, is produced. The basic salt, Hg6CrO6, or Hg2CrO4.2Hg2O, has been stated to result from the action of sodium hydroxide on the normal chromate, but this is denied by Fichter and Oesterheld, who maintain that the mercurous oxide formed is uncombined with chromate.

The double salt, K2Hg2(CrO4)2, has been described by Groger, who obtained it as golden yellow non-crystalline spangles containing absorbed potassium chromate, by adding a solution of mercurous nitrate to a concentrated solution of potassium chromate. Water decomposed it, giving a basic salt.


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