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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.
Chromic acid is jargon for a solution formed by the addition of sulfuric acid to aqueous solutions of dichromate. It consists at least in part of chromium trioxide. [3] The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium ...
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 ...
Potassium dichromate, Chromic acid, (K2CrO4), dipotassium salt. Identifiers CAS Number. ... This yellow solid is the potassium salt of the chromate anion.
Ammonium dichromate is an inorganic compound with the formula (NH 4) 2 Cr 2 O 7. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state , commonly known as hexavalent chromium .
This occurs during hydration of metal ions, so colorless anhydrous salts with an anion absorbing in the infrared can become colorful in solution. [81] Salts exist in many different colors, which arise either from their constituent anions, cations or solvates. For example: sodium chromate Na 2 CrO 4 is made yellow by the chromate ion CrO 2− 4.
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 .