Basic Lead Nitrates

Various basic lead nitrates have been described. They are obtained by the action of metallic lead, lead oxide, white lead, potassium hydroxide, ammonia, or certain basic oxides on lead nitrate solution, or by dissolving lead oxide in solutions of other metallic nitrates; i.e. either by adding hydroxide ions to lead nitrate or nitrate ions to lead hydroxide.

The following salts appear to exist; other products which have been described are probably mixtures.

Pb(NO₃)₂.PbO.H₂O or Pb(NO₃)OH.
2Pb(NO₃)₂.4PbO.3H₂O, formulated by Berzelius and Meissner as 6PbO.N₂O₅.3H₂O.
3Pb(NO₃)₂.7PbO.4 or 5H₂O.
Pb(NO₃)₂.5PbO.H₂O.
Pb(NO₃)OH is prepared by boiling the normal salt with an equal weight of lead oxide and water, and cooling, when it separates in crystals, which are sparingly soluble in cold, but more readily soluble in hot water. Carbon dioxide forms carbonate and the normal salt; gentle heat converts the compound into red lead.

The other salts are obtained by the action of lead hydroxide on potassium nitrate solution, or of ammonia on lead nitrate solution.

In addition to these, however, there are the two anhydrous basic salts formed during the careful ignition of solid lead nitrate, viz. 2Pb(NO₃)₂.PbO and Pb(NO₃)₂.2PbO.

A comparison of the solubilities of lead nitrate in water and in potassium and sodium nitrate solutions, as well as a study of the freezing-points of the simple and mixed solutions, leads to the conclusion that lead nitrate combines with alkali nitrates in solution to form complex ions, such as (KPbNO₃)^••, so that a reaction, such as

Pb(NO₃)₂ + KNO₃ ⇔ (KPbNO,)^•• + 2NO₃'

takes place in solution.

Lead nitrate forms with thiourea the compounds:

Pb₂(CSN₂H₄)₁₁(NO₃)₄ and Pb(CSN₂H₄)₂(NO₃)₂; and with pyridine Pb(NO₃)₂.2C₅H₅N, and Pb(NO₃)₂.3C₅H₅N.