Chemical elements
    Physical Properties
    Chemical Properties
      Cobaltous Fluoride
      Hydrated Cobaltous Fluoride
      Cobaltic Fluoride
      Cobaltous Chloride
      Cobaltic Chloride
      Cobaltous Bromide
      Cobaltous Iodide
      Cobalt Oxy-fluoride
      Cobalt Oxy-chloride
      Cobalt Chlorate
      Cobalt Perchlorate
      Cobalt Bromate
      Cobalt Iodate
      Cobalt Monoxide
      Cobaltous Hydroxide
      Tri-cobalt Tetroxide
      Cobalt Sesquioxide
      Hydrated Cobaltic Oxide
      Cobalt Dioxide
      Cobalt Monosulphide
      Tricobalt Tetrasulphide
      Cobalt Sesquisulphide
      Cobalt Disulphide
      Cobalt Polysulphides
      Cobaltous Sulphite
      Cobaltic Sulphite
      Cobalt Thiosulphate
      Cobalt Dithionate
      Cobalt Sulphate
      Ammonium Cobalt Sulphate
      Potassium Cobalt Sulphate
      Cobaltic Sulphate
      Ammonium Cobalt Alum
      Potassium Cobalt Alum
      Cobalt Subselenide
      Cobalt Selenide
      Tricobalt Tetraselenide
      Cobalt Sesquiselenide
      Cobalt Diselenide
      Cobalt Selenite
      Cobalt Diselenite
      Cobalt Triselenite
      Cobaltous Selenate
      Cobaltic Selenate
      Cobalt Sesquitelluride
      Cobalt Tellurite
      Cobalt Chromate
      Cobalt Dichromate
      Double Chromates
      Cobalt Molybdate
      Cobalt Nitride
      Cobalt Azoimide
      Potassium Cobaltous Nitrite
      Potassium Cobalti-nitrite
      Sodium Cobalti-nitrite
      Sodium Potassium Cobalti-nitrite
      Ammonium Cobalti-nitrite
      Barium Cobalti-nitrite
      Red Sodium Cobalti-nitrite
      Red Barium Cobalti-nitrite
      Red Strontium Cobalti-nitrite
      Zinc Cobalti-tri-nitrite
      Silver Cobalti-tri-nitrite
      Cobaltous Nitrate
      Cobaltic Nitrate
      Cobalt Subphosphide
      Cobalt Sesquiphosphide
      Tri-cobalt Diphosphide
      Tetra-cobalt Triphosphide
      Cobalt Hypophosphite
      Cobalt Phosphite
      Cobalt Metaphosphate
      Tri-cobalt Di-arsenide
      Cobalt Monarsenide
      Cobalt Tri-arsenide
      Cobalt Arsenites
      Cobalt Arsenates
      Cobalt Antimonide
      Cobalt Di-antimonide
      Cobalt Antimonate
      Cobalt Thio-antimonite
      Cobalt Carbide
      Cobalt Tetra-carbonyl
      Cobaltous Carbonate
      Basic Cobaltous Carbonates
      Cobaltic Carbonate
      Cobaltous Cyanide
      Potassium Cobalto-cyanide
      Nickel Cobalto-cyanide
      Cobaltous Cobalto-cyanide
      Zinc Cobalto-cyanide
      Cobalti-cyanic Acid
      Ammonium Cobalti-cyanide
      Barium Cobalti-cyanide
      Potassium Cobalti-cyanide
      Cobalt Cobalti-cyanide
      Cupric Cobalti-cyanide
      Ferrous Cobalti-cyanide
      Nickel Cobalti-cyanide
      Silver Cobalti-cyanide
      Lead Cobalti-cyanide
      Sodium Cobalti-cyanide
      Cobalt Thiocyanate
      Cobalt Subsilicide
      Cobalt Monosilicide
      Cobalt Disilicide
      Cobalt Orthosilicate
      Cobalt Fluosilicate
    PDB 1a0c-1epy
    PDB 1et4-1k7y
    PDB 1k98-1r6x
    PDB 1r8k-1v9b
    PDB 1vl3-212d
    PDB 222d-2eff
    PDB 2ehd-2j3z
    PDB 2j4j-2r1p
    PDB 2r2s-331d
    PDB 362d-3fqw
    PDB 3ft6-3igy
    PDB 3igz-3o0n
    PDB 3o0o-4req
    PDB 4xim-9icb

Cobalt Monoxide, CoO

Cobaltous Oxide, Cobalt Monoxide, CoO, may be obtained from cobaltie oxide by reduction in a current of ammonia, or of hydrogen at about 350° C. At higher temperatures metallic cobalt is obtained.

Cobaltous oxide also results when cobaltic oxide or cobalt carbonate is heated to redness in carbon dioxide or nitrogen; when cobalt itself is heated in nitric oxide to 150° C.; and when cobalt sulphate is heated to whiteness.

Obtained by any of the foregoing methods cobaltous oxide is a stable powder, greyish in colour, which on heating in air takes up oxygen forming cobalto-cobaltic oxide. Its density is about 5.68 when obtained by calcination from a higher oxide. Prepared from the sulphate it retains the crystalline form of the latter, and its density is 6.70. It is reduced to metallic cobalt when heated in carbon monoxide at temperatures above 450° C., or in hydrogen above 250° C. An allotropic modification of cobaltous oxide is formed by heating cobalto-cobaltic oxide with 2 to 3 per cent, of carbon at about 900° C. It is yellowish green in colour.6 Neither allotrope is magnetic.

When heated gently in air it yields tri-cobalt tetroxide, Co3O4. In hydrogen sulphide the oxysulphide CoO.CoS is produced.

It unites with acids to form cobaltous salts. It replaces ammonia in its salts and is dissolved by potassium hydroxide, yielding a deep blue solution.

Cobalt oxide unites with or forms solid solutions with many other metallic oxides at high temperatures. Thus, with alumina at 1100° C. a blue aluminate, CoO.Al2O3, is formed, whilst at higher temperatures a green compound, 4CoO.3Al2O3, is produced. With stannic oxide, cobalt oxide yields a dark green ortho-stannate, 2CoO.SnO2, or Co2SnO4. The same compound is produced by precipitating cobalt metastannate from a solution of a cobalt salt by addition of potassium metastannate, and heating the precipitate. The colour is then greenish blue, the blue tinge resulting from the excess of stannic oxide. With chromic oxide a green chromite, CoO.Cr2O3, is obtained; the vanadate and tantalate are likewise green, whilst the uranate is yellow.

Cobalt Blue consists essentially of oxides of cobalt and aluminium with more or less zinc oxide. It is obtained by calcining a mixture of alum and cobalt sulphate, and is used by artists in painting porcelain. Save for this it has now no commercial value. Cobalt blue is also known as Cobalt Ultramarine, Thenard's Blue, and King's Blue.

Cobalt Green or Rinmann's Green was discovered in the eighteenth century by a Swede named Rinmann, who obtained it by heating a mixture of zinc oxide and cobalt oxide. It can be obtained in a variety of other ways. Large crystals may be prepared by heating zinc oxide with cobalt carbonate to 1100° C., potassium chloride being used as a flux. The product is cooled in carbon dioxide when thin tabular crystals are usually obtained, green in colour, and of density 5.69. Analysis indicates a composition corresponding to CoO.4.8ZnO. It is not a definite chemical entity, but a solid solution of the two oxides in one another. Turquoise Green is similar, but contains some oxide of chromium in addition. Both pigments are used in porcelain painting. Cobalt Red is obtained in a similar manner to Rinmann's green, save that the zinc oxide in the latter is replaced by magnesium oxide.

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