Links for Chapter 13: Electrolysis
Video clips and animations
- Electrolytes and non-electrolytes
Lecture demonstration from Canadian lecturer Bob Burk looking at salt and sugar solutions. His demonstrations are always worth watching. However, under no circumstances should you try this at home, because he uses mains electricity to do the test. That is potentially lethal. In the lab, you would normally not use more than, say, a 6 volt battery and small bulb. YouTube
- Electrolysis of molten salts
An introduction to the electrolysis of melts - lead bromide and zinc chloride. It implies that bromine gas contains bromine atoms rather than diatomic molecules, and leaves some unanswered questions, but is otherwise good. It takes 5 minutes, but gives you a better view than you would ever get of the experiment in the lab. YouTube
- The electrolysis of sodium chloride solution
This comes from the same source as the electrolysis of molten salts above - 4 minutes this time. Again it doesn't state clearly that the hydrogen and chlorine produced are diatomic molecules rather than single atoms. YouTube
- The electrolysis of copper(II) sulfate solution
This brief video shows the formation of copper and oxygen from the electrolysis of copper(II) sulfate solution using carbon electrodes. This experiment is being done very quickly, with a high current density (found by dividing the current in amps by the surface area of the electrode actually in the solution). If it continued any longer, the copper wouldn't plate cleanly on to the electrode, but instead tends to form a dark brown-black "fur". To get good adhesion, you need a current density of around 30 mA per square centimetre of cathode immersed in the solution (that's about what is used for plating copper industrially). From Mike Thompson's ChemPics on YouTube.
Instructions for practical work
I have referred to practicalchemistry.org as a reliable source of instructions for experiments. If you find anything really good from other sources, could you let me know via the address on the about this site page of Chemguide.
- Electrolysis menu
Lots of electrolysis experiments.
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© Jim Clark 2009