Registration Dossier
Registration Dossier
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EC number: 215-158-8 | CAS number: 1308-14-1
Endpoint summary
Administrative data
Description of key information
Additional information
Chromium(III)hydroxide only occurs as hydrates. The substance precipitates as bluish grey green to dark green gelatinous solid at 20°C / 293.15 K and 1013 hPa. The trihydrate Cr(0H)3*3H20 is a blue-green powder at 20°C / 293.15 K and 1013 hPa or shining, vitrous and jet-black particles at 20 °C / 293.15 K and 1013 hPa. X-ray diffraction patterns with a Gandolfi camera using Cu Kα radiation show that the unheated and heated solids are amorphous.
The substance is decomposed under dehydration to chromium(III) oxide by heat. Therefore melting point and boiling point are not available. The substance is an ionic inorganic, thus the vapour presure is expected to be negligible. Chromium(III)hydroxide is an amphoteric hydroxide. The solubility curve is parabolic, depending on pH. The solubility is as follows: >pH 4: moderately soluble, pH 6.8 – 11.5: insoluble. > pH 11.5 slightly soluble. Freshly prepared Chromium(III)hydroxide underlies aging processes reducing its solubility with time.
Chromium(III)hydroxide is subject to hydrolysis, precipitation and complexation reactions including dissociation of several Cr(III) species depending on pH. Chromium hydroxide subject to dissociation in strongly acidic solution. Dissociation in neutral medium is very low caused by the very low water solubility of the substance at pH 6.8 - 11.5 and the very low equilibrium constant of the dissociation reaction.
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