232 HEAVY METALS OF GROUPS I AND II
in respect to its behavior towards strong acids and strong bases?
Write ionic equations.
- Write an equation for the reaction of calcium hypochlonte
with sodium carbonate solution. Trace through the reactions and
show what impurity would have gone through into the final
product if calcium hypochlorite had been used directly instead of
sodium hypochlorite.
PREPARATION 32
MERCUROUS NITRATE, HgNCVH^O
Mercury, like copper, will not dissolve in non-oxidizing acids,
but it does dissolve in nitric acid. Two oxides of mercury are
known, Hg 2 O and HgO, corresponding to the mercurous and mer-
curic salts. In order to obtain the nitrate corresponding to the
lower oxide, it is necessary merely to keep mercury present in
excess until after the acid is exhausted.
Materials: mercury, Hg, 25 grams = 0.125 F.W.
6N HN0 3 , 20 cc.
Apparatus: 300-cc. flask.
4-inch porcelain dish,
iron ring and ring stand.
Bunsen burner.
Procedure: Treat 25 grams of mercury in a flask in the hood with
20 cc. of 6 N HNO3, warming gently, until no further action takes
place. Allow to cool until the flask can be held in the hand, then
pour the solution away from any remaining globule of mercury
into a small dish, and leave to crystallize until the next day.
Spread the crystals out on a filter paper placed on a paper towel
and let them dry at room temperature. Put the product in a
cork-stoppered test tube as soon as it is dry.
QUESTIONS
- Treat 0.5 gram of the preparation with 20 cc. of cold water.
It does not dissolve to give a clear solution. Note the character of
the residue of basic salt. Add dilute nitric acid drop by drop,
until a clear solution is obtained. Explain why the presence of a
little nitric acid should enable us to get a clear solution.
