|
Vanadium Tetrafluoride
Vanadium(IV) fluoride (Vanadium, VFluorine, F4) is an inorganic compound of vanadium and fluorine. It is paramagnetic yellow-brown solid that is very hygroscopic. Unlike the corresponding vanadium tetrachloride, the tetrafluoride is not volatile because it adopts a polymeric structure. It decomposes before melting. Preparation and reactions VF4 can be prepared by treating VCl4 with hydrogen fluoride, HF: :VCl4 + 4 HF → VF4 + 4 HCl It was first prepared in this way. It decomposes at 325 °C, undergoing disproportionation to the vanadium trifluoride, tri- and Vanadium pentafluoride, pentafluorides: :2 VF4 → VF3 + VF5 Structure The structure of VF4 is related to that of SnF4, SnF4. Each vanadium centre is octahedral, surrounded by six fluoride ligands. Four of the fluoride centers bridging ligand, bridge to adjacent vanadium centres.Becker S., Muller B. G. ''Vanadium Tetrafluoride'', Angew. Chem. Intnl. Ed. Engl. 1990, vol. 29, page 406 References WebElements * Va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment. ''Deliquescent'' materials are sufficiently hygroscopic that they absorb so much water that they become liquid and form an aqueous solution. Etymology and pronunciation The word ''hygroscopy'' () uses combining forms of '' hygro-'' and '' -scopy''. Unlike any other ''-scopy'' word, it no longer refers to a viewing or imaging mode. It did begin that way, with the word ''hygroscope'' referring in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
