Titanium: the essentials
Titanium s a lustrous, white metal when pure. Titanium minerals are quite common. The metal has a low density, good strength, is easily fabricated, and has excellent corrosion resistance. The metal burns in air and is the only element that burns in nitrogen. It is marvellous in fireworks.
Titanium is resistant to dilute sulphuric and hydrochloric acid, most organic acids, damp chlorine gas, and chloride solutions. Titanium metal is considered to be physiologically inert.
Titanium is present in meteorites and in the sun. Some lunar rocks contain high concentrations of the dioxide, TiO2. Titanium oxide bands are prominent in the spectra of M-type stars.
Titanium: historical information
Titanium was discovered by the Reverend William Gregor in 1791, who was interested in minerals. He recognized the presence of a new element, now known as titanium, in menachanite, a mineral named after Menaccan in Cornwall (England). Several years later, the element was rediscovered in the ore rutile by a German chemist, Klaproth.
The pure elemental metal was not made until 1910 by Matthew A. Hunter, who heated TiCl4 together with sodium in a steel bomb at 700-800°C.
Titanium: physical properties
Titanium: orbital properties
Isolation: titanium is readily available from commercial sources so preparation in the laboratory is not normally required. In industry, reduction of ores with carbon is not a useful option as intractable carbides are produced. The Kroll method is used on large scales and involves the action of chlorine and carbon upon ilmenite (TiFeO3) or rutile (TiO2). The resultant titanium tetrachloride, TiCl4, is separated from the iron trichloride, FeCl3, by fractional distillation. Finally TiCl4 is reduced to metallic titanium by reduction with magnesium, Mg. Air is excluded so as to prevent contamination of the product with oxygen or nitrogen.
2TiFeO3 + 7Cl2 + 6C (900°C) → 2TiCl4 + 2FeCl3 + 6CO
TiCl4 + 2Mg (1100°C) → 2MgCl2 + Ti
Excess magensium and magneium dichloride is removed from the product bytreatment with water and hydrochloric acid to leave a titanium "sponge". This can be melted under a helium or argon atmosphere to allow casting as bars.