Chemical elements
  Lead
    Occurrence
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Lead Tetramethyl
      Lead Tetraethyl
      Lead Tetraphenyl
      Lead Ethoxide
      Lead Fluoride
      Lead Tetrafluoride
      Hydrofluoplumbic Acid
      Lead Chloride
      Lead Chloride Double Salts
      Basic Lead Chlorides
      Lead Tetrachloride
      Ammonium Plumbichloride
      Lead Chlorite
      Lead Chlorate
      Lead Perchlorate
      Lead Dibromide
      Double Salts of Lead Bromide
      Basic Lead Bromides
      Lead Bromate
      Lead Iodide
      Lead Iodide Complex Salts
      Basic Lead Iodides
      Lead Tetra-iodide
      Lead Iodate
      Lead Periodates
      Lead Suboxide
      Lead Monoxide
      Litharge
      Massicot
      Lead Hydroxides
      Lead Dioxide
      Plumbic Acids
      Hexahydroxyplumbic Acid
      Colloidal Plumbic Acid
      Potassium Plumbate
      Lead Plumbate
      Calcium Orthoplumbate
      Lead Orthoplumbate
      Red Lead
      Metaplumbic Acid
      Calcium Metaplumbate
      Lead Metaplumbate
      Basic Lead Plumbate
      Lead Sulphide
      Lead Sulphohalides
      Lead Polysulphide
      Lead Sulphite
      Lead Sulphates
      Lead Sulphate
      Basic Lead Sulphates
      Lead Hydrogen Sulphate
      Plumbic Sulphate
      Lead Persulphate
      Lead Thiosulphate
      Lead Dithionate
      Lead Selenide
      Lead Selenite
      Lead Selenate
      Lead Telluride
      Lead Tellurite
      Lead Azide
      Lead Azoimide
      Lead Hydrazoate
      Lead Imide
      Lead Hyponitrite
      Lead Nitrites
      Lead Nitrate
      Lead saltpetre
      Basic Lead Nitrates
      Lead Hypophosphite
      Lead Phosphite
      Lead Orthophosphate
      Lead Monohydrogen Phosphate
      Lead Dihydrogen Phosphate
      Lead Pyrophosphate
      Lead Metaphosphate
      Lead Arsenite
      Lead Orthoarsenate
      Lead Hydrogen Arsenate
      Lead Pyroarsenate
      Lead Antimonate
      Lead Carbonate
      White Lead
      Lead Formate
      Lead Acetate
      Sugar of Lead
      Complex Lead Acetates
      Plumbic Acetate
      Lead Tetra-acetate
      Lead Oxalate
      Lead Tartrate
      Lead Silicates
      Lead Borates
      Normal Lead Chromate
      Lead Dichromate
      Basic Lead Chromate
      Lead Molybdate
      Lead Tungstate
      Lead Metatungstate
      Lead Diuranate
      Lead Peruranate
    PDB 1afv-3qjk

Lead Acetate, Pb(C2H3O2)2






Lead Acetate (Sugar of Lead), Pb(C2H3O2)2.3H2O, has been known for four or five hundred years. It is prepared by dissolving lead oxide in acetic acid, and is formed slowly by the action of acetic acid and air upon lead. The trihydrate forms monoclinic crystals, isomorphous with those of barium and zinc acetates; it has a density of 2.50. The hydrated salt easily loses water when gently heated, melts at 75° C., and at 100° C. loses acetic acid as well as water, giving rise to a basic salt. The following are the aqueous vapour pressures of this salt at different temperatures:

Temperature ° C.12.515.818.320.921.330.1
Vapour Pressure, mm. Hg2.924.295.326.817.1414.91


The anhydrous salt has a density of 3.251, melts at 280° C., and when strongly heated evolves first acetic acid vapour, then carbon dioxide and acetone, and finally leaves a residue of pyrophoric lead.

If paper is soaked in lead acetate solution and dried, it smoulders like tinder when ignited. This may be due to the formation and combustion of pyrophoric lead.

The molecular heat of formation of the anhydrous salt is 232,600 calories.

Lead acetate is readily soluble in water, and much more soluble in hot than in cold water; 100 grams of water dissolve 50 grams of the salt at 25° C., 100 grams at 40° C., and 200 grams at 100° C.

The state of lead acetate in aqueous solution has been the subject of considerable investigation, as well as the cause of the solubility of lead sulphate in ammonium and sodium acetate solutions.

So far as ionisation of lead acetate takes place, it probably occurs in two stages, as with other salts of lead and of other bivalent metals, thus:

Pb(C2H3O2)2Pb(C2H3O2) + (C2H3O2)'
Pb(C2H3O2)Pb•• + (C2H3O2)'.

Noyes and Whitcomb have found that lead acetate solution is, however, much less ionised than the acetates of barium, manganese, nickel, cobalt, zinc, and cadmium under equivalent, conditions; and that, assuming dissociation into three ions, its degree of ionisation is only about 22 per cent, in decinormal solution.

This small degree of ionisation appears to be connected with the spontaneous formation of complex anions, which occurs also with other acetates, and to a less extent with chlorides, sulphates, and nitrates.

The addition of an alkali acetate to lead acetate solution, by increasing the concentration of the acetate ions, increases the concentration of these complex anions; and this fact, as will appear, affords an explanation of the solubility of lead sulphate in acetate solutions. The solubilities of lead sulphate in ammonium acetate solutions of different strengths at 25° C. have been estimated by Noyes and Whitcomb.

These same observers conclude that the lead is present in the acetate solution almost entirely in the non-ionised state, non-ionised lead acetate being formed by metathesis, thus:

PbSO4 + 2NH4 + 2C2H3O2' ⇔ Pb(C2H3O2)2 + 2NH4 + SO4'.

The solubility of lead sulphate in concentrated solutions of sodium and potassium acetates has been examined by Fox, who concludes that metathesis takes place, according to the above equation; but that complex acetates are formed, such as PbK2(C2H3O2)4, which probably would not exist in dilute solution; and that this salt, reacting with the potassium'sulphate in solution, would produce the sparingly soluble salt PbK2(SO4)2, which has been observed to crystallise.

Hydrated lead acetate dissolves in alcohol; 100 grams of alcohol dissolve 3.3 grams of the salt at 25° C. and 100 grams at 100° C.; 100 grams of glycerol dissolve 20 grams of lead acetate at 15° C.

Numerous basic acetates have been described, but probably only two are definite compounds.

The salt Pb(C2H3O2)OH, or Pb(C2H3O2)2.Pb(OH)2, is formed when lead oxide is treated with excess of lead acetate solution, by the partial decomposition of the neutral acetate solution with ammonia or alkalis, or by dissolving the salt Pb(C2H3O2)2.2Pb(OH)2 in a solution of the normal acetate.

The salt Pb(C2H3O2)2.2Pb(OH)2 is formed by treating lead acetate solution with excess of lead oxide, or by pouring a solution of lead acetate into excess of ammonia.

According to Sakabi, the only solid compounds that can exist in contact with lead acetate solutions at 25° C. are: Pb(C2H3O2)2.3H2O, Pb(C2H3O2)2.Pb(OH)2, and Pb(C2H3O2)2.2Pb(OH)2.


© Copyright 2008-2012 by atomistry.com