Chemical elements
    Physical Properties
    Chemical Properties
      Cerous hydride
      Cerous fluoride
      Cerous chloride
      Cerous oxychloride
      Cerous bromide
      Cerous iodide
      Cerous perchlorate
      Cerous bromate
      Cerous iodate
      Cerous oxide
      Cerous sesquioxide
      Cerous hydroxide
      Cerous sulphide
      Cerous persulphide
      Cerous oxysulphide
      Cerous sulphite
      Cerous sulphate
      Cerous dithionate
      Cerous selenite
      Cerous selenate
      Cerous chromate
      Cerous molybdate
      Cerous tungstate
      Cerous nitride
      Cerous nitrite
      Cerous nitrate
      Cerous hypophosphite
      Cerous orthophosphate
      Cerous vanadate
      Cerous carbide
      Cerous silicide
      Cerous carbonate
      Cerous thiocyanate
      Cerous platinocyanide
      Cerous oxalate
      Cerous silicate
      Ceric fluoride
      Ceric chloride
      Ceric iodate
      Ceroceric oxide
      Ceroceric hydroxide
      Ceric oxide
      Cerium dioxide
      Ceric hydroxide
      Perceric hydroxide
      Ceric hydrosulphate
      Ceric sulphate
      Ceric selenite
      Ceric chromate
      Ceric molybdate
      Ceric nitrate
      Ceric ammonium nitrate
      Ceric orthophosphate
      Ceric dihydrogen arsenate
      Ceric carbonate
      Perceric carbonate
      Ceric acetate
      Ceric oxalate
      Ceric acetylacetonate
      Ceric borate
    PDB 1ak8-1n65

Ceroceric hydrosulphate

When ceric oxide or hydroxide is heated with fairly concentrated sulphuric acid it is not quantitatively converted into ceric sulphate; oxygen is evolved and part of the ceric salt reduced to the cerous state. From the acid solution a beautiful red hexagonal crystalline salt may be readily obtained, and from the mother liquor normal ceric sulphate, Ce(SO4)2.4H2O, may then be separated in pale yellow crystals.

In addition to the preceding method of preparation, the red crystals may be obtained by mixing cerous sulphate with an excess of ceric sulphate and crystallising from fairly concentrated sulphuric acid.

The hexagonal crystals appear dark orange-coloured when large crystals are viewed in the direction of the principal axis, and orange-yellow when fine needles are similarly examined. Viewed parallel to the basal plane, the crystals appear to have a beautiful red colour. They may be heated to 230° without losing anything but their water of crystallisation.

The substance contains both cerous and ceric sulphates as well as sulphuric acid, and the latter cannot be eliminated at 130° in vacuo. It may therefore be described as a ceroceric hydrosulphate. The cerous sulphate may be replaced by the sulphates of the other rare earth elements, and Brauner has prepared the lanthanum, praseodymium., and neodymium salts. They are hexagonal, and isomorphous with one another and with the cerous salt. According to Brauner, they are acid salts of a complex cerisulphuric acid, H4.CeIV(SO4)4.12H2O, of the type HMIII.CeIV(SO4)4.12H2O (MIII = Ce, La, Pr, or Nd). It may be remarked that the acid sulphate of thorium has the composition Th(SO4)2. H2SO4 or H2Th(SO4)3, and not H4Th(SO4)4. On the other hand, the acid sulphates of the rare earth elements have formulae of the type M2III(SO4)3.3H2SO4 or H3[MIII(SO4)3], the ceric salt of which would be Ce3IV[MIII(SO4)3]4, or 3CeIV(SO4)2.2M2III(SO4)3, in harmony with the formula of Wyrouboff and Verneuil; it is then difficult, however, to account for the extra sulphuric acid present in the molecule.

If ceroceric hydrosulphate is a "complex" salt, it is not a very stable complex, for the addition of alkali leads to the initial precipitation of the violet ceroceric hydroxide.

It will be noticed that the formula assigned to ceroceric hydrosulphate by Meyer and Aufrecht only differs from Brauner's formula (1904) in the amount of water of crystallisation present. Too much significance should not, however, be attached to this agreement, for the analytical data upon which the formulae are based are of slender value, and at the present time the composition and constitution of this interesting compound must be regarded as undetermined.

Thus, even the atomic ratio CeIV: CeIII is uncertain. The analytical data given by Wyrouboff and Verneuil agree very well with the result CeIV: CeIII::3:4, and the data given by Meyer and Aufrecht and by Brauner agree at least as well with this ratio as with the ratio 1:1, which they adopt. Brauner's analyses of the lanthanum, praseodymium, and neodymium salts are also unsatisfactory, as Wyrouboff and Verneuil have justly remarked.

It is, perhaps, worth while to point out that the formula 3Ce(SO4)2.2Ce2(SO4)3.2H2SO4.42H2O agrees with the analytical data given by Brauner and by Wyrouboff and Verneuil at least as well as do their own formulae. This is readily seen from the following table of results: -

Per cent, ofCalculated from the Formula ofFound by
Brauner.W. and V.H.F.V.L.Brauner.W. and V.
Active oxygen.0.910.790.780.820.840.79

which serves to illustrate the difficulties attaching to the investigation of the composition of ceroceric hydrosulphate.

Finally, it may be mentioned that Brauner has described a ceroceric sulphate, CeIII[CeIV(SO4)4]3.44H2O, and the corresponding lanthanoceric salt.

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