Chemical elements
  Lanthanum
    Isotopes
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    Production
    Application
    Chemical properties
      Lanthanum chloride
      Lanthanum iodide
      Lanthanum perchlorate
      Lanthanum bromate
      Lanthanum iodate
      Lanthanum periodate
      Lanthanum sesquioxide
      Lanthana
      Lanthanum hydroxide
      Lanthanum peroxide
      Lanthanum persulphide
      Lanthanum sulphate
      Lanthanum dithionate
      Lanthanum selenite
      Lanthanum selenate
      Lanthanum chromate
      Lanthanum azide
      Lanthanum hydrazoate
      Lanthanum trinitride
      Lanthanum nitrate
      Lanthanum phosphite
      Lanthanum orthophosphate
      Lanthanum hydrogen pyrophosphate
      Lanthanum metaphosphate
      Lanthanum arsenates
      Lanthanum carbonate
      Lanthanum thiocyanate
      Lanthanum platinocyanide
      Lanthanum acetate
      Lanthanum oxalate
    PDB 1djg-2rpv

Lanthanum sulphate, La2(SO4)3






Of all the rare earth sulphates, Lanthanum sulphate, La2(SO4)3, is the most difficult to decompose completely by heat. Its specific heat (0°-100°) is 0.1182.

One part of the anhydrous sulphate dissolves in 6 parts of ice-cold water; from the solution at 0° C. a hydrate, La2(SO4)3.16H2O, may be crystallised.

The hexagonal enneahydrate, La2(SO4)3.9H2O, is the only hydrate stable in contact with the solution between 0° and 100°. It is readily prepared by warming a 15 per cent, ice-cold solution of lanthanum sulphate to 30°. The solubility diminishes with the temperature as follows: -

Temp. °C.14°18°30°50°75°100°
Grams of La2(S04)33.02.62.11.91.61.00.7


The figures represent grams of anhydrous salt per 100 grams of water.

A hexahydrate, La2(SO4)3.6H2O, is said to crystallise from a solution in aqueous sulphuric acid (Frerichs and Smith).

The acid sulphate, La(HSO4)3, and the basic sulphate, La2O3.SO3, are known. The following double salts have been described: -

La2(SO4)3.Cs2SO4.2H2O; 3La2(SO4)3.2Cs2SO4;
La2(SO4)3.Rb2SO4.2H2O; La2(SO4)3.Rb2SO4; 3La2(SO4)3.2Rb2SO4;
La2(SO4)3.K2SO4.2H2O; La2(SO4)3.3K2SO4; La2(SO4)3.5K2SO4;
La2(SO4)3.Na2SO4.2H2O;
La2(SO4)3.(NH,)2SO4.8H2O; 2La2(SO4)3.5(NH4)2SO4; La2(SO4)3.5(NH4)2SO4.

Lanthanum sulphate also combines with hydrazine sulphate. The diminution in solubility of lanthanum sulphate brought about by the addition of potassium, sodium, or ammonium sulphate will be seen from the following data, given by Barre, and denoting grams of anhydrous salts present in solution per 100 grams of water (solid phases not stated by Barre): -

Temperature 16.5°.Temperature 18°.Temperature 18°.
K2SO4.La2(SO4)3.Na2SO4.La2(SO4)3.(NH4)2SO4.La2(SO4)3.
0.002.210.002.130.002.13
0.250.730.401.004.010.39
0.500.270.690.358.730.28
0.850.190.770.3018.240.25
1.030.051.140.1327.890.48
1.160.022.480.0436.110.28
2.500.003.800.0247.490.14
......5.550.0265.290.011


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