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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+
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. Because of the very high melting point of chromium, chromium thermite casting is impractical. Heating with chlorine and carbon yields chromium(III) chloride and ...
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−
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 ...
Iron(III) chloride – FeCl 3; Iron(III) fluoride – FeF 3; Iron(III) oxalate – C 6 Fe 2 O 12; Iron(III) oxide – Fe 2 O 3; Iron(III) nitrate – Fe(NO 3) 3 (H 2 O) 9; Iron(III) sulfate – Fe 2 (SO 4) 3; Iron(III) thiocyanate – Fe(SCN) 3; Iron(II,III) oxide – Fe 3 O 4; Iron ferrocyanide – Fe 7 (CN) 18; Prussian blue (Iron(III ...
The trichromium cation is encountered with a variety of anions, such as chloride and nitrate. Data in the table above are for the chloride hexahydrate, [Cr 3 O(O 2 CCH 3) 6 (OH 2) 3]Cl(H 2 O) 6. The cation in basic iron acetate is isostructural with the cation in basic chromium acetate. Both feature octahedral metal centers conjoined by oxo and ...
The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO 4 ·7H 2 O) and iron(III) chloride (FeCl 3). The former is one of the most readily available sources of iron(II), but is less stable to aerial oxidation than Mohr's salt ((NH 4) 2 Fe(SO 4) 2 ·6H 2 O). Iron(II) compounds tend to be oxidized to iron(III ...