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org07 Photo reaction of hexane and bromine: Radical Substitution
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Left: For groups
of students 25 ml of hexane are mixed with 2 drops of bromine in
a 50-ml dropper bottle.
Photo 2: 1 ml samples
of this bromine solution are distributed to each student in 5-ml vials
closed by stoppers which are protected by thin plastic film.
Photo 3: The mixture
is exposed to bright light to start the reaction (sun, overhead or slide
projector).
Observations
Photo
4: The brown
liquid has lost its colour. Right photo: Humid universal
indicator paper is made red by fumes above the liquid.
Explanations:
The
colour of bromine disappeared, because this brown substance was consumed:
Hydrogen bromide gas (HBrg) and bromo hexane were formed
C6H14(l) + Br2(l)
-----light----> C6H13Br(l) + HBr(g)
Hydrobromic acid (HBraq)
appeared on the surface of the wetted indicator paper.
Hexane and its product differed
by a hydrogen atom which was replaced ( =substituted) by a Br atom.
Such reactions are called
substitution
reactions.
More about this reaction.
Reactions of the products
HBr(g)
and
C6H13Br(l):
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