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The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
Vanadium ion is rather large and some complexes achieve coordination numbers greater than 6, as is the case in [V(CN) 7] 4−. Oxovanadium(V) also forms 7 coordinate coordination complexes with tetradentate ligands and peroxides and these complexes are used for oxidative brominations and thioether oxidations.
The name was based on the wide range of colors found in vanadium compounds. Del Río's lead mineral was ultimately named vanadinite for its vanadium content. In 1867, Henry Enfield Roscoe obtained the pure element. Vanadium occurs naturally in about 65 minerals and fossil fuel deposits. It is produced in China and Russia from steel smelter slag.
Dissolution of vanadium pentoxide in strongly basic aqueous solution gives the colourless VO 3− 4 ion. On acidification, this solution's colour gradually darkens through orange to red at around pH 7. Brown hydrated V2O5 precipitates around pH 2, redissolving to form a light yellow solution containing the [VO 2 (H 2 O) 4] + ion. The number and ...
If acid is slowly added to a solution of Na 3 VO 4, the colour gradually deepens through orange to red before brown hydrated V 2 O 5 precipitates around pH 2. These solutions contain mainly the ions HVO 4 2− and V 2 O 7 4− between pH 9 and pH 13, but below pH 9 more exotic species such as V 4 O 12 4− and HV 10 O 28 5− (decavanadate ...
Vanadium(IV) oxide or vanadium dioxide is an inorganic compound with the formula VO 2. It is a dark blue solid. It is a dark blue solid. Vanadium (IV) dioxide is amphoteric , dissolving in non-oxidising acids to give the blue vanadyl ion , [VO] 2+ and in alkali to give the brown [V 4 O 9 ] 2− ion, or at high pH [VO 4 ] 4− . [ 4 ]
Vanadyl perchlorate or vanadyl triperchlorate is a golden yellow coloured liquid or crystalline compound of vanadium, oxygen and perchlorate group. The substance consists of molecules covalently bound and is quite volatile; it ignites organic solvents on contact and explodes at temperatures above 80 °C.
The compound is prepared by the addition of ammonium salts to solutions of vanadate ions, generated by dissolution of V 2 O 5 in basic aqueous solutions, such as hot sodium carbonate. The compound precipitates as a colourless solid. [3] [4] This precipitation step can be slow.