Synthetic Inorganic Chemistry

308 ELEMENTS OF GROUP V

PREPARATION 56
ANTIMONY TRICHLORIDE FROM STIBNITE, SbCl 3
(BY-PRODUCT: ANTIMONY OXYCHLORIDE)
Native antimony sulphide (stibnite) dissolves quite readily in
hydrochloric acid, yielding antimony trichloride,

Sb 2 S 3 + 6HC1 = 2SbCl 3 + 3H 2 S

If the solution so obtained is distilled, steam and hydrochloric
acid pass off at first, later a mixture of hydrochloric acid and anti-
mony trichloride, and finally pure antimony trichloride.
Antimony trichloride hydrolyzes with a moderate amount of
water, giving a precipitate according to the reactions

SbCl 3 + 2H 2 O = Sb(OH) 2 Cl j + 2HC1

Sb(OH) 2 Cl = SbOCl + H 2 O

with more water a further hydrolysis takes place:

4SbOCl + H 2 O = Sb 4 O 6 Cl 2 + 2HC1

The product obtained in this preparation by mixing the next to the
last distillates with a considerable amount of water has the latter
composition. This compound, however, if repeatedly boiled with
fresh portions of water may be made to undergo complete hydroly-
sis, leaving finally only Sb 2 O 3.
Pure antimony trichloride melts at 73° and boils at 223°.
Materials: stibnite, Sb 2 S 3 , 168 grams = 0.5 F.W.
12 N commercial concentrated HC1, 840 cc.
shredded asbestos suspended in water,
unglazed porcelain.
Apparatus: 8-inch porcelain dish.
suction filter and trap bottle.
wide 6-inch test tube.
350-cc. retort or distilling flask.
6-inch sand bath.
asbestos paper.
1-liter flask.
2-liter common bottle.
5-inch watch glass.
Bunsen burner.