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Chromate anions (CrO 2− 4) and dichromate (Cr 2 O 7 2−) anions are the principal ions at this oxidation state. They exist at an equilibrium, determined by pH: 2 [CrO 4] 2− + 2 H + ⇌ [Cr 2 O 7] 2− + H 2 O. Chromium(VI) oxyhalides are known also and include chromyl fluoride (CrO 2 F 2) and chromyl chloride (CrO 2 Cl 2). [6]
Cr 2 O 3 + 3 CrO 3 → 5 CrO 2 + O 2. Along with many other oxides, it is used as a compound when polishing (also called stropping) the edges of knives, razors, surfaces of optical devices etc. on a piece of leather, balsa, cloth or other material. It is available in powder or wax form, and in this context it is known as "green compound".
Commonly three electrons are added to a chromium atom, reducing it to oxidation state +3. In acid solution the aquated Cr 3+ ion is produced. Cr 2 O 2− 7 + 14 H + + 6 e − → 2 Cr 3+ + 7 H 2 O ε 0 = 1.33 V. In alkaline solution chromium(III) hydroxide is produced. The redox potential shows that chromates are weaker oxidizing agent in ...
Chromate anions (CrO 2− 4) and dichromate (Cr 2 O 7 2−) anions are the principal ions at this oxidation state. They exist at an equilibrium, determined by pH: 2 [CrO 4] 2− + 2 H + ⇌ [Cr 2 O 7] 2− + H 2 O. Chromium(VI) oxyhalides are known also and include chromyl fluoride (CrO 2 F 2) and chromyl chloride (CrO 2 Cl 2). [21]
4 HCrO 4 − + 3 RCH 2 OH + 16 H + + 11 H 2 O → 4 [Cr(H 2 O) 6] 3+ + 3 RCOOH. The inorganic products are green, characteristic of chromium(III) aquo complexes. [2] Like many other oxidations of alcohols by metal oxides, the reaction proceeds via the formation of a mixed chromate ester: [3] [4] These esters have the formula CrO 3 (OCH 2 R) −
Fractional oxidation states are often used to represent the average oxidation state of several atoms of the same element in a structure. For example, the formula of magnetite is Fe 3 O 4, implying an average oxidation state for iron of + 8 / 3 . [17]: 81–82 However, this average value may not be representative if the atoms are not ...
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 oxidation states are also maintained in articles of the elements (of course), and systematically in the table {{Infobox element/symbol-to-oxidation-state}} See also [ edit ]