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Chromate salts contain the chromate anion, CrO 2− 4. Dichromate salts contain the dichromate anion, Cr 2 O 2− 7. They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible.
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.
Silver dichromate is a chemical compound with the formula Ag 2 Cr 2 O 7. It is insoluble in water and decomposes when treated with hot water. Its anion has a charge of -2.
In 2005–06, potassium dichromate was the 11th-most-prevalent allergen in patch tests (4.8%). [12] Potassium dichromate is one of the most common causes of chromium dermatitis; [13] chromium is highly likely to induce sensitization leading to dermatitis, especially of the hand and forearms, which is chronic and difficult to treat ...
The change in equilibrium is visible by a change from yellow (chromate) to orange (dichromate), such as when an acid is added to a neutral solution of potassium chromate. At yet lower pH values, further condensation to more complex oxyanions of chromium is possible. Both the chromate and dichromate anions are strong oxidizing reagents at low pH ...
The dichromate ion, Cr 2 O 2− 7, is predominant in more concentrated solutions, except at high pH. The species H 2 CrO 4 and HCr 2 O − 7 are not shown as they are formed only at very low pH. Predominance diagrams can become very complicated when many polymeric species can be formed, [10] such as in vanadates, molybdates, and tungstates ...
sodium chromate Na 2 CrO 4 is made yellow by the chromate ion CrO 2− 4. potassium dichromate K 2 Cr 2 O 7 is made red-orange by the dichromate ion Cr 2 O 2− 7. cobalt(II) nitrate hexahydrate Co(NO 3) 2 ·6H 2 O is made red by the chromophore of hydrated cobalt(II) [Co(H 2 O) 6] 2+. copper(II) sulfate pentahydrate CuSO 4 ·5H 2 O is made ...
Sodium dichromate is the inorganic compound with the formula Na 2 Cr 2 O 7. However, the salt is usually handled as its dihydrate Na 2 Cr 2 O 7 ·2 H 2 O . Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compounds and materials based on chromium are prepared from this salt. [ 1 ]