Search results
Results from the WOW.Com Content Network
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 666 °C. [1] These structures are complex, although the chromate ion adopts the typical tetrahedral geometry. [2]
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.
3 c 2 h 5 oh + 2 k 2 cr 2 o 7 + 8 h 2 so 4 → 3 ch 3 cooh + 2 cr 2 (so 4) 3 + 2 k 2 so 4 + 11 h 2 o The excess dichromate is determined by titration against sodium thiosulfate . Adding the amount of excess dichromate from the initial amount, gives the amount of ethanol present.
For example, [Ti(H 2 O) 6] 4+ is unknown: the hydrolyzed species [Ti(OH) 2 (H 2 O) n] 2+ is the principal species in dilute solutions. [11] With the higher oxidation states the effective electrical charge on the cation is further reduced by the formation of oxo-complexes.
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.
Substance Formula 0 °C 10 °C 20 °C 30 °C 40 °C 50 °C 60 °C 70 °C 80 °C 90 °C 100 °C Barium acetate: Ba(C 2 H 3 O 2) 2: 58.8: 62: 72: 75: 78.5: 77: 75
Paraffin wax, for example, has a specific heat of about 2500 J⋅K −1 ⋅kg −1 but a molar heat capacity of about 600 J⋅K −1 ⋅mol −1. The molar heat capacity is an "intensive" property of a substance, an intrinsic characteristic that does not depend on the size or shape of the amount in consideration.
The specific heat of the human body calculated from the measured values of individual tissues is 2.98 kJ · kg−1 · °C−1. This is 17% lower than the earlier wider used one based on non measured values of 3.47 kJ · kg−1· °C−1.