Vanadium thermodynamic data

Crystal field theory is one of several chemical bonding models and one that is applicable solely to the transition metal and lanthanide elements. The theory, which utilizes thermodynamic data obtained from absorption bands in the visible and near-infrared regions of the electromagnetic spectrum, has met with widespread applications and successful interpretations of diverse physical and chemical properties of elements of the first transition series. These elements comprise scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper. The position of the first transition series in the periodic table is shown in fig. 1.1. Transition elements constitute almost forty weight per cent, or eighteen atom per cent, of the Earth (Appendix 1) and occur in most minerals in the Crust, Mantle and Core. As a result, there are many aspects of transition metal geochemistry that are amenable to interpretation by crystal field theory. 

Vanadium Tetraiodide. VI4 is unstable and has not been isolated, but its absorption spectrum has been observed in the range 230 - 500 nm in the vapor, and thermodynamic data for its dissociation into VI3 and I2 have been determined (AH° = 104.8kcalm-, AS° = 98.4kJm- ). 

Sulfur oxides in the FCC regenerator flue gas can react with these alkaline earth metals to form sulfates. On the basis of thermodynamic data, the formation of calcium and barium sulfates is favored over the formation of vanadates at typical regenerator conditions[l 1,12]. The other trap materials may or may not be affected by sulfur competition, depending on the SOx concentration and regenerator conditions. In any case, the effect of sulfur competition can not be overlooked when designing effective vanadium traps. 

Griffiths, R., Pryde, 1. and Righini Brand, A., Phase diagram and thermodynamic data for the hydrogen/vanadium system. Journal of the Chemical Society Faraday Transactions I, 1972, 68 p. 2344-2349. 

The Ag-V system has been critically assessed by Korb [2004Kor], The calculated phase diagram is in good agreement with the experimental thermodynamic data. The small solubility of Ag in solid vanadium is reproduced well by the calculations. 

Thermodynamic data are also available for the solid oxide phase of vanadium(II), VO(s), from which the solubility of the phase can be ascertained. 

Pure oxide or hydroxide phases of vanadium(IV) do not appear to exist naturally. Nonetheless, solubility data are available for two vanadium(IV) oxide phases, V204(s) and V204-2H20(s) (or equivalently VO(OH)2(s)). Thermodynamic data have also been reported for V204(s). 

Table 11.3 Thermodynamic data for vanadium(lll) species at 25 °C and comparison with data avaiiabie in the iiterature.

Table 11.5 Literature thermodynamic data for vanadium species at 25 °C.

The solid-state and solution chemistry of triethanolamine complexes has been investigated. While the solid-state structure was maintained in organic solvent (38), a different structure was observed in aqueous solution.262 170 NMR spectroscopy was used to demonstrate that the two oxo groups were different and in combination with H and 13C NMR data, defined the structure as (39).262 Speciation studies and a detailed characterization of this class of compounds were important because the ligand is a commonly used buffer in biology and the complexes are model systems for interactions with proteins.61,263 The thermodynamic parameters were determined for several derivatized diethanolamine ligand-vanadium(V) complexes, and represent some of the few vanadium complexes for which such parameters are known.62 The structure of (nitrilotriacetato)dioxovanadate was reinvestigated.2 4... 

Although 3208 " can oxidize Fe t rapidly, it is unable to oxidize vanadium species C for kinetic reasons. Look up and use appropriate data to show that oxidations of any reduced vanadium species by S208 are thermodynamically favored (and therefore this one must be kineti-cally slow since it does not proceed). 

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