How does the structure change as water molecules are added?Īnhydrous CoCl 2 has the same structure as cadmium chloride, CdCl 2. Silica gel is sometimes supplied containing some cobalt chloride, which indicates the water content – blue when it is dry, pale pink when the air round it is damp. When you heat the gel, it loses the water so you can reuse it. Yes, they are put in with various consumer products, like electrical goods, shoes and handbags, to absorb water, because silica gel can absorb up to about 40% of its weight in water. Silica gel? You mean the stuff that comes in little bags with a warning not to eat them? It can be used as a humidity indicator in weather-measuring instruments, as well as in self-indicating silica gel. You can get an indicator paper – like litmus paper but containing cobalt chloride - which changes colour from blue to pink in the presence of water. This can again be reversed by adding water. If you warm pink CoCl 2.6H 2O gently – up to 150☌ or so - it will gradually lose water forming the violet CoCl 2.2H 2O, then blue anhydrous CoCl 2. You can reverse these changes with solid cobalt chloride crystals. First the purple dihydrate, CoCl 2.2H 2O, forms and then at higher humidity the pink hexahydrate CoCl 2.6H 2O is the product. Anhydrous cobalt chloride, CoCl 2, is blue in colour. It is an unusual material in the way it changes colour, particularly in the presence of water. Why be interested in cobalt chloride anyway? You can also obtain isolated CoCl 2 molecules in matrices of argon and nitrogen at low temperatures too (the unreactive Ar atoms and N 2 molecules come between CoCl 2 molecules, ‘spacing them out’). Electron diffraction measurements show that it is a linear molecule with Co-Cl distance of 2.113 Å. True, but this picture shows the structure of an isolated CoCl 2 molecule in the gas phase at around 1000 K. Why? Everyone knows that a metal and a non-metal form ionic bonds and have giant structures. More about the Cobalt Chloride in Wikipedia.COBALT CHLORIDE - Molecule of the Month June 2016 - HTML-only versionĬOBALT CHLORIDE A drug used to dope racehorses that's also a water indicator. Cobalt chloride is one method used to induce pulmonary arterial hypertension in animals for research and evaluation of treatment efficacy. Cobalt chloride is a banned substance under the Australian Thoroughbred Racing Board. Cobalt supplementation is not banned and therefore would not be detected by current anti-doping testing. Cobalt chloride is an established chemical inducer of hypoxia-like responses such as erythropoiesis. Invisible ink: when suspended in solution, cobalt(II) chloride can be made to appear invisible on a surface when that same surface is subsequently exposed to significant heat (such as from a handheld heat gun or lighter) the ink permanently/ irreversibly changes to blue. Cobalt(II) chloride catalyzes cross-coupling of aryl halides or vinyl halides with aryl Grignard reagents in excellent yields. Cobalt chloride is useful for producing invisible ink as it turns blue when heated and becomes invisible once it gets cooled. Cobalt chloride is an indicator for water in desiccants, owing to the reversible hydration/dehydration coupled with distinct color change. In the anhydrous form, it finds use in electroplating of cobalt, in organic chemistry and is a precursor to cobaltocene, (bis(cyclopentadienyl)cobalt(II), which is a good reducing agent. hydrated) ApplicationsĬobalt(II) chloride is used in humidity indicator in weather instruments. Desiccants such as silica gel can incorporate cobalt chloride to indicate when it is "spent" (i.e. It is impregnated into a paper to make test strips for detecting moisture in solutions, or more slowly, in air/gas. The colour change is from a shade of blue when dry, to a pink when hydrated, although the shade of colour depends on the substrate and concentration. Arte Fo supplies cobalt (II) chloride anhydrous with 99,8% purity (metals basis) in several amounts.Ĭobalt chloride is a common visual moisture indicator due to its distinct colour change when hydrated. It is generally supplied in bead form and should be handled carefully as it is a suspected carcinogen. Analytical research gradeĬobalt (II) chloride anhydrous, also known as Cobaltous Chloride, is a beautiful sky blue color.
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