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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.
Chromium(III) hydroxide is a gelatinous green inorganic compound with the chemical formula Cr(OH) 3. It is a polymer with an undefined structure and low solubility. It is amphoteric, dissolving in both strong alkalis and strong acids. [2] In alkali: Cr(OH) 3 + OH − → CrO − 2 + 2 H 2 O In acid: Cr(OH) 3 (OH 2) 3 + 3 H + → Cr(OH 2) 6 3+
Chromium(II) oxide (CrO) is an inorganic compound composed of chromium and oxygen. [1] It is a black powder that crystallises in the rock salt structure. [2] Hypophosphites may reduce chromium(III) oxide to chromium(II) oxide: H 3 PO 2 + 2 Cr 2 O 3 → 4 CrO + H 3 PO 4. It is readily oxidized by the atmosphere. CrO is basic, while CrO 3 is ...
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 alkaline solution than in acid solution. [6] CrO 2− 4 + 4 H 2 O + 3 e − → Cr(OH) 3 + 5 OH −
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 ...
Cr 2 O 3 has the corundum structure, consisting of a hexagonal close packed array of oxide anions with 2 ⁄ 3 of the octahedral holes occupied by chromium. Similar to corundum, Cr 2 O 3 is a hard, brittle material (Mohs hardness 8 to 8.5). [4] It is antiferromagnetic up to 307 K, the Néel temperature. [5] [6] It is not readily attacked by acids.
The structure of the pyridine complex has been determined crystallographically. [2] Adducts with other N-heterocycles have also been characterized similarly. [3] Aqueous chromium(VI) oxide peroxide decomposes in a few seconds, turning green as chromium(III) compounds are formed. [4] 2 CrO(O 2) 2 + 7 H 2 O 2 + 6 H + → 2 Cr 3+ + 10 H 2 O + 7 O 2
Numerous organic compounds have other common names, often originating in historical source material thereof. The systematic IUPAC name is not always the preferred IUPAC name, for example, lactic acid is a common, and also the preferred, name for what systematic rules call 2-hydroxypropanoic acid.