Lithium monoxide, Li₂O

The Lithium monoxide, Li₂O prepared by heating the metal in oxygen at 200° C. always contains the peroxide, but it can be obtained pure by heating the carbonate at 780° to 800° C. in a current of hydrogen, or by heating the hydroxide at 780° C. or the nitrate to fusion under similar conditions. The volatility of the monoxide necessitates careful regulation of the temperature.

Lithium monoxide forms a white, amorphous, more or less porous mass. Its melting-point is unknown, owing to its volatility at high temperatures. For the density of an impure specimen, Brauner and Watts found at 15° C. the value 2.102. At a high temperature it attacks platinum, but its great stability is exemplified by its indifference towards hydrogen, carbon, and carbon monoxide.

Lithium monoxide is slowly attacked by water, with formation of the intensely alkaline solution of the hydroxide. The heat evolved is given by the equation

[Li₂O]+Aq.=2LiOH,Aq.+31.20 Cal.

Since the heat evolved by solution of 2 gram-atoms of lithium in water is 106.4 Cal., and the heat of formation of water is 68.3 Cal., the heat of formation of the oxide from its elements is given by the equation

2[Li]+(O)=[Li₂O] +143.5 Cal.