Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
ammonia : NH3
bromine : Br2
antimony : Sb
Class:
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elem=Br,Sb
redox
Summary:
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When antimony is added to liquid bromine, then a violent reaction occurs, even
with appearance of sparks.
Description:
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Put a few drops of bromine in a test tube and then add a small amount of
granules of elemental antimony: The smaller pieces of antimony react quickly
with the bromine, with appearance of sparks/fire. The larger pieces sink to the
bottom and also react violently, giving rise to boiling of the bromine, but no
fire appears from these pieces of antimony.
After some time, the bottom of the test tube is filled with a thick dark brown
paste-like mass, with some mobile liquid bromine still above it. When the
bromine is allowed to evaporate, a brown paste-like mass remains. This
paste-like mass is antimony bromide, heavily contaminated with bromine.
Add a few ml of 5% household ammonia: A vigorous reaction starts, with
formation of nitrogen gas (the remains of bromine oxidize the ammonia).
Furthermore, the solid paste-like mass becomes white and the liquid becomes
turbid. The white solid most likely is hydrated antimony (III) oxide, or maybe
an oxybromide of antimony (III).
Decant the turbid liquid: A lot of white material remains, sticking to the
glass.
Add some concentrated hydrochlorid acid: The white material slowly dissolves.
There also is some white smoke, due to formation of ammonium chloride from the
remains of the ammonia and the hydrochloric acid.