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The hydrogen chromate ion, HCrO 4 −, is a weak acid: HCrO − 4 ⇌ CrO 2− 4 + H +; pK a ≈ 5.9. It is also in equilibrium with the dichromate ion: 2 HCrO − 4 ⇌ Cr 2 O 2− 7 + H 2 O. This equilibrium does not involve a change in hydrogen ion concentration, which would predict that the equilibrium is independent of pH.
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 ·2H 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]
ion has a similar radius (63 pm) to Al 3+ (radius 50 pm), and they can replace each other in some compounds, such as in chrome alum and alum. Chromium(III) tends to form octahedral complexes. Commercially available chromium(III) chloride hydrate is the dark green complex [CrCl 2 (H 2 O) 4]Cl.
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. It is a salt consisting of ammonium ions and dichromate ions.
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 ...
Chromate and dichromate have equal concentrations. Setting [CrO 2− 4] equal to [Cr 2 O 2− 7] in Eq. 3 gives [CrO 2− 4] = 1 / β 2 [H +] 2 . The predominance diagram is interpreted as follows. The chromate ion is the predominant species in the region to the right of the green and blue lines. Above pH ~6.75 it is always the ...
Download as PDF; Printable version; ... Chromate and dichromate, ions; ... an ion; Tetrachromate, an ion; Chromate conversion coating, a method for passivating metals ...