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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]
When heated strongly, it decomposes with the evolution of oxygen. 4 K 2 Cr 2 O 7 → 4 K 2 CrO 4 + 2 Cr 2 O 3 + 3 O 2 When an alkali is added to an orange-red solution containing dichromate ions, a yellow solution is obtained due to the formation of chromate ions ( CrO 2− 4 ).
Predominance diagram for chromate. In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium.. 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.
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
The cited Andersland Charts include corresponding water content percentages for easy measurements. The TPRC Data Book has been quoting de Vries with values of 0.0251 and 0.0109 W⋅cm −3 ⋅Kelvin −1 for the thermal conductivities of organic and dry mineral soils respectively but the original article is free at the website of their cited ...
It is very insoluble in water, but is soluble in acids: 2 BaCrO 4 + 2 H + → 2 Ba 2+ + Cr 2 O 7 2− + H 2 O K sp = [Ba 2+][CrO 4 2−] = 2.1 × 10 −10. It can react with barium hydroxide in the presence of sodium azide to create barium chromate(V). The reaction releases oxygen and water.
Using a work input equals to a fraction f of the heat input is equivalent relative to the choice of the reactions to operate a pure similar thermochemical cycle but with a hot source with a temperature increased by the same proportion f. Naturally, this decreases the heat-to-work efficiency in the same proportion f. Consequently, if one want a ...
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