Vanadium - chemistry.

Vanadium - chemistry. I INTRODUCTION Vanadium, symbol V, silver-white metallic element with an atomic number of 23. Vanadium is one of the transition elements of the periodic table (see Periodic Law). It was discovered in 1801 in Mexico by Andrés Manuel del Rio, but it was mistaken for a form of chromium. Vanadium was rediscovered in about 1830 by the Swedish chemist Nils Gabriel Sefström. The element was named for Vanadis, goddess of beauty and love in Scandinavian mythology. II PROPERTIES AND OCCURRENCE Vanadium takes a high polish and is one of the hardest of all metals. It melts at about 1910°C (about 3470°F), boils at about 3407°C (about 6164°F), and has a specific gravity of 6.11. The atomic weight of vanadium is 50.94. Vanadium is soluble in nitric and sulfuric acids and insoluble in hydrochloric acid, dilute sodium hydroxide, and dilute alcohol. Vanadium forms several acidic oxides, the most important of which are the dark green trioxide, V2O 3, and the orange pentoxide, V2O 5. Other important compounds include vanadium monosulfide, VS; vanadium trisulfide, V2S3; vanadium dichloride, VCl2; vanadium trichloride, VCl3; vanadium dihydroxide, V(OH)2; and metavanadic acid, HVO3. Vanadium ranks about 19th in abundance of the elements in Earth's crust. It is never found in the pure state, but occurs in combination with various minerals throughout the world. Vanadium-ore minerals in the United States are roscoelite, found in Colorado; vanadinite, found in Arizona and New Mexico; and carnotite, found in Colorado and Utah. Major producers of vanadium include the United States, Russia, and South Africa. III USES Because of its hardness and great tensile strength, the metal is used in many alloys such as ferrovanadium, nickel vanadium, and chrome vanadium. Chrome-vanadium steels are used in the production of springs and in transmission gears and other engine parts. Titanium-vanadium alloys are used for missile cases, jet-engine housings, and nuclear-reactor components. As a catalyst, vanadium has largely replaced platinum in the manufacture of sulfuric acid and is employed widely as a photographic developer, as a reducing agent, and as a drying agent in various paints. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.