Synthetic Inorganic Chemistry

212 ELEMENTS OF GROUP III

into the first one with stirring and observe the decolorization and

the evolution of a gas. Again compare with the action of hydrogen

peroxide.

PREPARATION 25
HYDRATED ALUMINUM CHLORIDE, A1C1 3 -6H 2 O
A solution of aluminum chloride can be prepared by the action
of hydrochloric acid on the metal, but if this solution is evaporated
to dryness, the solid that is left is the oxide instead of the chloride.
Hydrolysis is prevented by hydrochloric acid, and the hydrated
chloride can be crystallized from an acid solution. In this prepa-
ration the solution is saturated with hydrochloric acid, which not
only drives back hydrolysis but also reduces the solubility of the
salt.
Anhydrous aluminum chloride can be prepared by the action
of dry chlorine on aluminum; in its properties it is very similar to
aluminum bromide, which is the subject of the next preparation.

Materials: aluminum turnings, 13.5 grams = 0.5 F.W.

12 AT HCl, 125 cc.

rock salt, NaCl, 90 grams.

36iVH 2 SO 4 , 175 cc.

shredded asbestos suspended in water,

sodium hydroxide pellets for the desiccator.

Apparatus: 500-cc. flask.

suction filter and marble.

2-liter flask for generator (Fig. 23 on page 191).

4-inch porcelain dish.

desiccator.

pan of ice and water.

Procedure: Place the aluminum turnings in a 500-cc. flask; add
50 cc. of water and then the 12 N HCl drop by drop until a vigorous
reaction has started and finally as rapidly as may be without pro-
ducing too violent a reaction. The 125 cc. of acid should just
suffice to dissolve the metal. Unless it is perfectly clear, filter the
solution through asbestos on a suction filter (Note 4 (d), page 8)
and return it to the 500-cc. flask. Fit up the hydrogen chloride
generator and connections so that the gas will pass first through
a washing bottle containing a little 12 N HCl and provided with a