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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.
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.
Naturally occurring chromium is composed of four stable isotopes; 50 Cr, 52 Cr, 53 Cr and 54 Cr, with 52 Cr being the most abundant (83.789% natural abundance). 50 Cr is observationally stable , as it is theoretically capable of decaying to 50 Ti via double electron capture with a half-life of no less than 1.3 × 10 18 years.
Cr 2 O 3: chromium(III) oxide eskolaite: 1308-38-9 Cr 2 (SO 4) 3: chromium(III) sulfate: 10101-53-8 Cr 2 S 3: chromium(III) sulfide: 12018-22-3 Cr 2 Se 3: chromium(III) selenide: Cr 2 (TeO 4) 3: chromium(III) tellurate: Cr 2 Te 3: chromium(III) telluride: 12053-39-3 Cr 3 As 2: chromium(II) arsenide: Cr 3 C 2: chromium(II) carbide: 12012-35-0 Cr ...
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 −
Similarly, color is due to the energy absorbed by the compound, when an electron transitions from the HOMO to the LUMO. Lycopene is a classic example of a compound with extensive conjugation (11 conjugated double bonds), giving rise to an intense red color (lycopene is responsible for the color of tomatoes ).
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 ...