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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+
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
A large number of chromium(III) compounds are known, such as chromium(III) nitrate, chromium(III) acetate, and chromium(III) oxide. [33] Chromium(III) can be obtained by dissolving elemental chromium in acids like hydrochloric acid or sulfuric acid, but it can also be formed through the reduction of chromium(VI) by cytochrome c7. [34] The Cr 3+
The Pourbaix diagram for chromium in pure water, perchloric acid, or sodium hydroxide [1] [2] 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 ...
An amphiprotic molecule (or ion) can either donate or accept a proton, thus acting either as an acid or a base. Water , amino acids , hydrogencarbonate ion (or bicarbonate ion) HCO − 3 , dihydrogen phosphate ion H 2 PO − 4 , and hydrogensulfate ion (or bisulfate ion) HSO − 4 are common examples of amphiprotic species.
The primary chromium ore is the mixed metal oxide chromite, FeCr 2 O 4, found as brittle metallic black crystals or granules. Chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms iron(III) oxide, Fe 2 O 3:
Chrome alum. Chromium alum is produced from chromate salts or from ferrochromium alloys. Concentrated aqueous solutions of potassium dichromate can be reduced, usually with sulfur dioxide but also with alcohols or formaldehyde, in the presence of sulfuric acid at temperatures <40 °C.
Chromium(II) Cr 2+ bright blue Chromium(III) Cr 3+ blue-green-grey Chromium(III) hydroxide: Cr(OH) 6 3− yellowish Monochromate: CrO 2− 4 yellow Dichromate: Cr 2 O 2− 7 orange Manganese(II) Mn 2+ pale pink Manganese(III) Mn 3+ crimson Manganate(V) MnO 3− 4 deep blue Manganate(VI) MnO 2− 4 dark green Manganate(VII) (permanganate) MnO ...