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The photos were done using potassium dichromate in earlier times when the
high cancinogen potential
was not yet known.
* Sulfuric
acid is very corrosive, *Experiemnt for a chemistry teacher. * Use a tray.
* Do not forget your goggles!
During oxidation
of ethanol (methylated spirit) with acidic potassium permanganate solution
each ethanol molecule splitted off two H-atoms resulting in the formation of
ethanal. In
the following experiment you will take primary, secondary and tertiary butanol
to learn about isomerism.
Material
Dropper bottles with primary, secondary,
tertiary butanole, concentrated sulfuric acid, diluted potassium permanganate
solution, three small ampoulles.
Experiment
1. Mix one drop of each of the butanol samples with 3 drops of
the potassium permanganate solution.
2.
Add 1 drop of concentrated sulfuric acid to each of the samples and mix.
Observation
The pink colour of permanganate only
disappears in the samples of primary and secondary butanol.
Explanation
Molecules of primary and secondary alcohols are electron donors in direct redox
reactions, permanganate ions are electron acceptors. The blueish colour indicates
chromium ions (Cr3+(aq)).