Simple synthesis of tungsten(VI) oxide starting from a light bulb’s filament

Abstract

Tungsten(VI) oxide can be easily synthesized starting from a standard light bulb. The reaction consists in the oxidation at high temperatures (T ≈ 8776; 2000 – 3000° C) of a tungsten filament in presence of air; conditions which can be easily achieved by connecting a broken light bulb (but with its intact filament) to an AC-power supply of 110 volts. The vapor of WO₃ is condensed into a beaker in a quantity enough to be characterized by infrared spectroscopy. The experiment is very funny, inexpensive and allows to the teacher to link several topics in current chemistry and physics of the tungsten oxides, such as their nomenclature and technological applications (i.e. electrochromic devices, gasochromic sensors, superalloys or as it is used in home: As a “simple” emisor of light!).