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Although insoluble in water, it reacts with acid to produce salts of hydrated chromium ions such as [Cr(H 2 O) 6] 3+. [11] It is also attacked by concentrated alkali to yield salts of [Cr(OH) 6] 3−. When heated with finely divided carbon or aluminium, it is reduced to chromium metal: Cr 2 O 3 + 2 Al → 2 Cr + Al 2 O 3
It can be prepared by treating chromium metal with fluorine at 400 °C and 200 bar pressure. The peroxochromate(V) is another example of the +5 oxidation state. Potassium peroxochromate (K 3 [Cr(O 2) 4]) is made by reacting potassium chromate with hydrogen peroxide at low temperatures. This red brown compound is stable at room temperature but ...
4 CrO 3 → 2 Cr 2 O 3 + 3 O 2. It is used in organic synthesis as an oxidant, often as a solution in acetic acid, [9] or acetone in the case of the Jones oxidation. In these oxidations, the Cr(VI) converts primary alcohols to the corresponding carboxylic acids and secondary alcohols to ketones. The reactions are shown below: Primary alcohols ...
The formula of this compound can be written more descriptively as [Cr(H 2 O) 6] 2 (SO 4) 3 ·6H 2 O. Six of the eighteen water molecules in this formula unit are water of crystallization. Hydrated chromium(III) sulfate, Cr 2 (SO 4) 3 ·15(H 2 O), (CAS #10031-37-5) is a green solid that also readily dissolves in water. It is obtained by heating ...
Further condensation reactions can occur in strongly acidic solution with the formation of trichromates, Cr 3 O 2− 10, and tetrachromates, Cr 4 O 2− 13. [2] All polyoxyanions of chromium(VI) have structures made up of tetrahedral CrO 4 units sharing corners. [3] The hydrogen chromate ion, HCrO 4 −, is a weak acid: HCrO − 4 ⇌ CrO 2−
The reaction stoichiometry implicates the Cr(IV) species "CrO 2 OH −", which comproportionates with the chromic acid to give a Cr(V) oxide, which also functions as an oxidant for the alcohol. [ 6 ] The oxidation of the aldehydes is proposed to proceed via the formation of hemiacetal -like intermediates, which arise from the addition of the O ...
Chromium(III) oxide, Cr 2 O 3 Chromium dioxide (chromium(IV) oxide), CrO 2 , which includes the hypothetical compound chromium(II) chromate Chromium trioxide (chromium(VI) oxide), CrO 3
Potassium hypochromate decomposes in water to form chromium(III) oxide and potassium chromate when alkali is not present or low. [1] Potassium hypochromate also reacts with acids such as hydrochloric acid to form chromium(III) oxide, potassium chromate, and potassium chloride: [2] 6 K 3 CrO 4 + 10 HCl → 4 K 2 CrO 4 + Cr 2 O 3 + 5 H 2 O + 10 KCl