Chemical elements
  Lithium
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Lithium hydride
      Lithium chloride
      Lithium bromide
      Lithium iodide
      Lithium iodide tetrachloride
      Lithium hypochlorite
      Lithium chlorate
      Lithium perchlorate
      Lithium bromate
      Lithium iodate
      Lithium periodates
      Lithium monoxide
      Lithium peroxide
      Lithium hydroxide
      Lithium monosulphide
      Lithium polysulphides
      Lithium sulphite
      Lithium sulphate
      Lithium persulphate
      Lithium thiosulphate
      Lithium dithionate
      Lithium selenide
      Lithium selenite
      Lithium selenate
      Lithium chromate
      Lithium permanganate
      Lithium molybdates
      Lithium nitride
      Lithium hydrazoate
      Lithamide
      Lithium nitrite
      Lithium nitrate
      Lithium phosphide
      Lithium orthophosphate
      Lithium pyrophosphate
      Lithium metaphosphate
      Lithium arsenide
      Lithium meta-arsenite
      Lithium arsenate
      Lithium antimonide
      Lithium antimonate
      Lithium carbide
      Lithium carbonate
      Lithium percarbonate
      Lithium cyanide
      Lithium thiocyanate
      Lithium silicide
      Lithium silicates
      Lithium borates

Lithium peroxide, Li2O2






Addition of alcohol to the aqueous solution obtained by the interaction of hydrogen peroxide and lithium hydroxide precipitates the crystalline product Li2O2,H2O2,3H2O, a substance converted by drying over phosphoric anhydride into the anhydrous peroxide, Li2O2. The method resembles that employed in the preparation of the peroxides of the alkaline-earth-metals. The combustion of lithium in oxygen yields only a small proportion of peroxide, a distinction from sodium. The peroxide boils at 258° C.

The heat of formation of the peroxide from the monoxide and oxygen is given by the equation

[Li2O]+(O)=[Li2O2]+7.97 Cal.,

the corresponding equations for the peroxides of calcium, strontium, and barium being

[CaO]+(O)=[CaO2]+4.11 Cal.,
[SrO] + (O)=[SrO2] + 13.07 Cal.,
[BaO]+(O) =[BaO2] +18.36 Cal.

In this respect lithium displays close analogy to the alkaline-earth- metals, occupying a position between calcium and strontium. Further analogy is shown by the heat of formation of lithium peroxide from its elements

2[Li] + (O2)=[Li2O2] + 151.29 Cal.,

a value closely approximating to that of calcium peroxide,

[Ca]+(O2) =[CaO2] +150.43 Cal.

Divergence from the other alkali-metals is made evident by the fact that sodium peroxide has a considerably lower heat of formation -

2[Na]+(O2) =[Na2O2] +117.69 Cal.


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