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Cobalt blue is a blue pigment made by sintering cobalt (II) oxide with aluminium (III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt (II) oxide-aluminium oxide, or cobalt (II) aluminate, CoAl 2 O 4. Cobalt blue is lighter and less intense than the (iron-cyanide based) pigment Prussian blue.
Color of chemicals. The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
A flame test is relatively quick test for the presence of some elements in a sample. The technique is archaic and of questionable reliability, but once was a component of qualitative inorganic analysis. The phenomenon is related to pyrotechnics and atomic emission spectroscopy. [1] The color of the flames is understood through the principles of ...
Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, somewhat brittle, gray metal .
Cobalt violet is the only truly lightfast purple pigment with relatively strong color saturation. All other light-stable purple pigments are dull by comparison. The high price of the pigment and the toxicity of cobalt have limited its use. In the 1860s, the popularity of using violet colors suddenly rose among painters and other artists. [7]
Cobalt is a very intense colouring agent and very little is required to show a noticeable amount of colour. Cobalt glass plates are used as an optical filter in flame tests to filter out the undesired strong yellow light emitted by traces of sodium, and expand the ability to see violet and blue hues, [2] similar to didymium glass.
Cobalt phosphate is the inorganic compound with the formula Co 3 (PO 4) 2. It is a commercial inorganic pigment known as cobalt violet. [2] Thin films of this material are water oxidation catalysts. [3] A swatch of cobalt violet, popular among the French impressionists.
Blue pigments are natural or synthetic materials, usually made from minerals and insoluble with water, used to make the blue colors in painting and other arts. The raw material of the earliest blue pigment was lapis lazuli from mines in Afghanistan, that was refined into the pigment ultramarine. Since the late 18th and 19th century, blue ...