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When hydrated the colour changes to a light pink/purple. Cobalt chloride is a common visual moisture indicator due to its distinct colour change when hydrated. The colour change is from some shade of blue when dry, to a pink when hydrated, although the shade of colour depends on the substrate and concentration.
Anhydrous cobalt(II) chloride is blue, while the hexahydrate is magenta in colour. [1] Because the color change of cobalt(II) chloride in different hydrates, it can be used to manufacture color-changing silica gel. Anhydrous cobalt halides react with nitric oxide at 70~120 °C to generate [Co(NO) 2 X] 2 (X = Cl, Br or I).
Predicting the color of a compound can be extremely complicated. Some examples include: Cobalt chloride is pink or blue depending on the state of hydration (blue dry, pink with water) so it is used as a moisture indicator in silica gel. Zinc oxide is white, but at higher temperatures becomes yellow, returning to white as it cools.
The cobalt based HIC producers says that if a humidity indicator is considered an article in the EC definition and therefore has no labeling requirements if the content of cobalt(II) chloride by weight is <0.25%. The T (toxic) and R49 (may cause cancer if inhaled) is not applicable because a humidity indicator cannot be inhaled.
When a visible indication of the moisture content of the silica gel is required, ammonium tetrachlorocobaltate(II) (NH 4) 2 [CoCl 4] or cobalt(II) chloride CoCl 2 is added. [6] This will cause the gel to be blue when dry and pink when hydrated. [6] Due to a link between the cobalt chloride and cancer, it has been forbidden in Europe for use in ...
Cosmic Cobalt has been a favorite color for artists of every era. Getty Images/Wikimedia Commons Artists throughout history—from Vermeer and Klimt to Miro and Mondrian—have used the color ...
Cobalt(III) chloride or cobaltic chloride is an unstable and elusive compound of cobalt and chlorine with formula CoCl 3. In this compound, the cobalt atoms have a formal charge of +3. [1] The compound has been reported to exist in the gas phase at high temperatures, in equilibrium with cobalt(II) chloride and chlorine gas.
The cobalt chloride mentioned above occurs as [Co(H 2 O) 6] 2+ and Cl −. In tin chloride, each Sn(II) center is pyramidal (mean O/Cl−Sn−O/Cl angle is 83°) being bound to two chloride ions and one water. The second water in the formula unit is hydrogen-bonded to the chloride and to the coordinated water molecule.