Chemical elements
    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
      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 sulphate, Li2SO4

The hydrated Lithium sulphate, Li2SO4,H2O, is obtained in monoclinic plates by evaporating a solution of sulphuric acid neutralized with lithium carbonate. Its density is 2.02 to 2.06. The anhydrous salt is said to have been prepared by Retgers, its melting-point being given by Huttner and Tammann as 859° C., by Ramsay and Eumorfopoulos as 853° C., and by Muller as 843° C. Its density is 2.21.

Lithium sulphate is readily soluble in water. The heat of formation in dilute aqueous solution from lithium hydroxide and sulphuric acid is given by the equation

2LiOH,Aq.+H2SO4,Aq.=Li2SO4,Aq.+31.29 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 sulphuric acid from its elements is 192.92 Cal., and its heat of solution in water is 17.85 Cal., the heat of formation of the sulphate in dilute solution from the elements is given by the expression

2[Li] + [S]+2(O2)+Aq. =Li2SO4,Aq.+348.46 Cal.

Taking 6.05 Cal. as the heat of solution of anhydrous lithium sulphate, the value given by Thomsen, the equation for the heat of formation of the anhydrous sulphate becomes

2[Li]+ [S]+ 4(O) = [Li2SO4]+342.41 Cal.

For the heat of solution of the hydrate, Li2SO4,H2O, Thomsen gives the value 3.41 Cal., and for its heat of hydration the equation is

[Li2SO4]+H2O=Li2SO4,H2O+2.64 Cal.

References are appended to investigations on double sulphates with sodium, potassium, ammonium, and copper. Muller has prepared a double sulphate with rubidium, Li2SO4,Rb2SO4, melting at 730° C., and one with caesium, Li2SO4,Cs2SO4, melting at 729° C. Bergius has described a crystalline acid sulphate, Li2SO4,7H2SO4, which melts about 12° C. Lescoeur mentions lithium hydrogen sulphate, LiHSO4, which forms deliquescent crystals, melting at 120° C. Other double sulphates of lithium and hydrogen are Li2SO4,7H2SO4, melting at 13.6° C.; Li2SO4,2H2SO4, unstable at its melting-point; and Li2SO4,H2SO4, unstable at its melting-point, 170.5° C. (by extrapolation).

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