(^278) ELEMENTS OF GROUP IV
PREPARATION 46
LEAD NITRATE, Pb(NO 3 ) 2
Lead nitrate is one of the most readily prepared salts of lead,
since it is of moderate solubility and can be obtained in well-
formed anhydrous crystals, Pb(NO 3 ) 2. In it lead appears in its
usual state of oxidation, which corresponds to that of the oxide
PbO; indeed, the salt is actually prepared by treating this oxide
(litharge) with nitric acid.
A saturated solution contains for each 100 grams of water the given
number of grams of lead nitrate
Temperature.
Pb(NO 3 ) 2 ....
0°
36
10°
44
18°
51
25°
56
50°
79
100°
127
Materials: litharge, PbO, 56 grams = 0.25 F.W.
6 N nitric acid.
Apparatus: 400-cc. beaker.
8-inch crystallizing dish,
iron ring and ring stand.
Bunsen burner.
Procedure: Take 56 grams, or 0.25 F.W., of litharge, PbO. Cal-
culate the amount of 6 N nitric acid which would be necessary to
convert it into lead nitrate and the amount of water needed to dis-
solve the salt thus formed. Proceed to prepare lead nitrate,
striving to obtain good crystals of as large a size as possible.
The solution which is set to crystallize should be slightly acid —
enough to redden litmus. If insufficient nitric acid was used, the
excess of PbO would have dissolved somewhat in the hot con-
centrated Pb(NO 3 ) 2 solution forming the basic salt PbOHNO 3
which would separate as a fine granular or flaky precipitate when
the solution cooled.
QUESTIONS
- Explain why lead nitrate should be less soluble in dilute
nitric acid than in pure water. - Add a few drops of ammonium hydroxide to 1 cc. of lead