Search results
Results From The WOW.Com Content Network
It can be prepared by treating chromium metal with fluorine at 400 °C and 200 bar pressure. The peroxochromate(V) is another example of the +5 oxidation state. Potassium peroxochromate (K 3 [Cr(O 2) 4]) is made by reacting potassium chromate with hydrogen peroxide at low temperatures. This red brown compound is stable at room temperature but ...
The hydrogen chromate ion may be protonated, with the formation of molecular chromic acid, H 2 CrO 4, but the pK a for the equilibrium H 2 CrO 4 ⇌ HCrO − 4 + H + is not well characterized. Reported values vary between about −0.8 and 1.6. [4] The dichromate ion is a somewhat weaker base than the chromate ion: [5]
Chromyl chloride can be prepared by the reaction of potassium chromate or potassium dichromate with hydrogen chloride in the presence of concentrated sulfuric acid, followed by distillation. [3] [4] K 2 Cr 2 O 7 + 6 HCl → 2 CrO 2 Cl 2 + 2 KCl + 3 H 2 O. The sulfuric acid serves as a dehydration agent.
The structure of nickel chromate is the same as for chromium vanadate, CrVO 4. Crystals have an orthorhombic structure with unit cell sizes a = 5.482 Å, b = 8.237 Å, c = 6.147 Å. The cell volume is 277.6 Å 3 with four formula per unit cell. [5] [7] Nickel chromate is dark in colour, unlike most other chromates which are yellow. [3]
It is a red-brown paramagnetic solid. It is the potassium salt of tetraperoxochromate(V), one of the few examples of chromium in the +5 oxidation state and one of the rare examples of a complex stabilized only by peroxide ligands. [2] This compound is used as a source of singlet oxygen. [1]
Structure of CrO(O 2) 2 (pyridine).Hydrogen atoms bonded to carbon atoms are omitted. Color code: Cr = gray, C= black, H = white, O= red, N = blue. Chromium(VI) oxide peroxide is formed by the addition of acidified hydrogen peroxide solutions to solutions of metal chromates or dichromates, such as sodium chromate or potassium dichromate.
For compounds containing an oxyanion of chromium in oxidation state of +3; For other compounds of chromium(III) as a means of distinguishing a chemical species such as hexacyanochromite(III). [Cr(CN) 6] 3− from an analogous compound in which chromium is a different oxidation state. The mineral chromite is an iron chromium oxide with empirical ...
The oxide is also formed by the decomposition of chromium salts such as chromium nitrate, or by the exothermic decomposition of ammonium dichromate. (NH 4) 2 Cr 2 O 7 → Cr 2 O 3 + N 2 + 4 H 2 O. The reaction has a low ignition temperature of less than 200 °C and is frequently used in “volcano” demonstrations. [9]