Doktor Klawonn
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Electrolysis of zinc bromide
Introduction
Electrolysis of zinc bromide is a very simple experiment. The products are easy to observe. In school chemistry, it can be carried out directly after
the electrolysis of copper (II) chloride, the analogous chemical equation is then easier to draft.
Chemicals and apparatus
- U tube
- carbon electrodes
- zinc bromide
- destilled water
- stand
- wire
- electric power supply
Warning
In this experiment, bromine is produced.
Experimental
zinc bromide is dissolved in destilled water.[1] The resulting solution is filled into a U-tube to two thirds height.[2] Carbon electrodes are placed
into the sides of the U-tube. The electrodes are connected to the power supply.
 
Bromine is produced at the anode, indicated by a spreading yellow color. Greyish zinc is deposited at the catode.
 
 
The deposited zinc dissolves in HCl.
 
Sum reaction is:
ZnBr<sub>2</sub> --> Zn + Br<sub>2</sub>
Remarks
[1] The use of tap water may result in a turbid solution.
[2] This leaves room for the electrodes.
Links
- This experiment in a video
- The analogous experiment electrolysis of copper (II) chloride
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LanthanumK
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The dilute yellow bromine solution you see is probably about as dangerous as a bleach solution. Pure elemental bromine is not produced.
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roamingnome
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if elemental zinc can be produced this is interesting. Can you test the isolated zinc for hydrogen evolution.
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Doktor Klawonn
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[rquote=roamingnome]...if elemental zinc can be produced this is interesting. Can you test the isolated zinc for hydrogen evolution.
[/rquote]
This is shown in the very last photo, you can also see it at the end of the youtube video (see above under "Links").
@ LanthanumK
You are right, this experiment is not very dangerous. Nevertheless elemental bromine is produced indeed.
[Edited on 22-5-2011 by Doktor Klawonn]
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