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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 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.
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−
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. Unlike the classic thermite reaction involving iron oxides, the chromium oxide thermite creates few or no sparks, smoke or sound, but glows brightly.
Chromium trioxide (Chromic acid) – CrO 3; Chromium(II) chloride (chromous chloride) – CrCl 2; Chromium(II) sulfate – CrSO 4; Chromium(III) chloride – CrCl 3; Chromium(III) nitrate – Cr(NO 3) 3; Chromium(III) oxide – Cr 2 O 3; Chromium(III) sulfate – Cr 2 (SO 4) 3; Chromium(III) telluride – Cr 2 Te 3; Chromium(IV) oxide – CrO 2 ...
[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. Stable adducts of the type CrO(O 2) 2 L include those with L = diethyl ether, 1-butanol, ethyl acetate, or amyl acetate. They form by adding a layer of the ...
2 O + 3 e − → Cr(OH) 3 + 5 OH − (ε 0 = −0.13 V) Sodium chromate (Na 2 CrO 4) Chromium(VI) compounds in solution can be detected by adding an acidic hydrogen peroxide solution. The unstable dark blue chromium(VI) peroxide (CrO 5) is formed, which can be stabilized as an ether adduct CrO 5 ·OR 2. [21] Chromic acid has the hypothetical ...
The formula, Cu 2 CO 3 (OH) 2 shows that it is halfway between copper carbonate and copper hydroxide. Indeed, in the past the formula was written as CuCO 3 ·Cu(OH) 2. The crystal structure is made up of copper, carbonate and hydroxide ions. [37] The mineral atacamite is an example of a basic chloride. It has the formula, Cu 2 Cl(OH) 3.