Nitrogen ammonium nitrite . thermal

Molecular nitrogen is obtained by fractional distillation of air (the boiling points of liquid nitrogen and liquid oxygen are -196°C and -183°C, respectively). In the laboratory, very pure nitrogen gas can be prepared by the thermal decomposition of ammonium nitrite ... 

A solution of ammonium nitrite is usually obtained by mixing equimolar solutions of ammonium chloride and sodium nitrite since the solid is not thermally stable. On heating the mixed solution, it decomposes to water and nitrogen. The kinetics of the thermal decomposition can be readily followed by measuring at intervals the volume of nitrogen evolved from a thermostatted solution. Since a solution of ammonium nitrite exhibits absorption peaks in the u.v., it is likely that u.v. irradiation may increase the rate of gas evolution i.e. the rate of decomposition. 

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