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2 CrO 2− 4 + 2 H + ⇌ Cr 2 O 2− 7 + H 2 O. The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration of chromium. [notes 1] The chromate ion is the predominant species in alkaline solutions, but dichromate can become the predominant ion in acidic solutions.
Two crystalline forms are known, both being very similar to the corresponding potassium sulfate. Orthorhombic β-K 2 CrO 4 is the common form, but it converts to an α-form above 66 °C. [1] These structures are complex, although the chromate ion adopts the typical tetrahedral geometry. [2]
Calcium chromate is an inorganic compound with the formula CaCrO 4, i.e. the chromate salt of calcium.It is a bright yellow solid which is normally found in the dihydrate form CaCrO 4 ·2H 2 O.
CrO 2− 4 + 4 H 2 O + 3 e − → Cr(OH) 3 + 5 OH − (ε 0 = −0.13 V) Sodium chromate (Na 2 CrO 4) Chromium(VI) compounds in solution can be detected by adding an acidic hydrogen peroxide solution. The unstable dark blue chromium(VI) peroxide (CrO 5) is formed, which can be stabilized as an ether adduct CrO 5 ·OR 2. [6] Chromic acid has ...
2Cr 2 O 3 + 4 Na 2 CO 3 + 3 O 2 → 4 Na 2 CrO 4 + 4 CO 2. This process converts the chromium into a water-extractable form, leaving behind iron oxides. Typically calcium carbonate is included in the mixture to improve oxygen access and to keep silicon and aluminium impurities in an insoluble form. The process temperature is typically around ...
Silver chromate is an inorganic compound with formula Ag 2 CrO 4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate).
Monoclinic lead chromate is used in paints under the name chrome yellow, and many other names. [2] Lead chromate adopts the monazite structure, meaning that the connectivity of the atoms is very similar to other compounds of the type MM'O 4. Pb(II) has a distorted coordination sphere being surrounded by eight oxides with Pb-O distances ranging ...
[2] The hashemite crystals are not composed of pure barium chromate but instead contain some small sulfur content as well. The different crystals contain a range of sulfur impurities ranging from the more pure dark crystals, Ba 1.00 (Cr 0.93 , S 0.07 ) 1.00 O 4 , to the less pure light crystals, Ba 1.00 (Cr 0.64 , S 0.36 ) 1.00 O 4 .