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Chromium dioxide or chromium(IV) oxide is an inorganic compound with the formula CrO 2. It is a black synthetic magnetic solid. [3] It once was widely used in magnetic tape emulsion. [4] With the increase in popularity of CDs and DVDs and more recently digital media, the use of chromium(IV) oxide has declined.
Predominance diagram for chromate. In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium.. 2 CrO 2− 4 + 2 H + ⇌ Cr 2 O 2− 7 + H 2 O. The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration of chromium.
Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist. [3] [4]
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Potassium peroxochromate is prepared by treating potassium chromate with hydrogen peroxide at 0 °C: . 2 CrO 2− 4 + 8 H 2 O 2 → 2 [Cr(O 2) 4] 2− + 8 H 2 O. The intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V): [3] [4]
Oxidation numbers are fundamental to the chemical nomenclature of ionic compounds. For example, Cu compounds with Cu oxidation state +2 are called cupric and those with state +1 are cuprous. [4]: 172 The oxidation numbers of elements allow predictions of chemical formula and reactions, especially oxidation-reduction reactions. The oxidation ...
The Cr 2 (OAc) 4 (H 2 O) 2 molecule contains two atoms of chromium, two ligated molecules of water, and four acetate bridging ligands.The coordination environment around each chromium atom consists of four oxygen atoms (one from each acetate ligand) in a square, one water molecule (in an axial position), and the other chromium atom (opposite the water molecule), giving each chromium centre an ...
2Cr 2 O 3 + 4 Na 2 CO 3 + 3 O 2 → 4 Na 2 CrO 4 + 4 CO 2. This process converts the chromium into a water-extractable form, leaving behind iron oxides. Typically calcium carbonate is included in the mixture to improve oxygen access and to keep silicon and aluminium impurities in an insoluble form. The process temperature is typically around ...