Microscale Chemistry Experimentation for Teachers
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19.
Oxidation of ethanol by acidic dichromate solution
* Left: 10 drops of
ethanol, 10 drops of potassium dichromate solution and 2 drops of
conc. sulfuric acid
are mixed in
a stoppered vial.
* Middle: As soon
as the colour has changed from orange to blue green,
a tissue paper
with colourless Schiff reagent is fixed above the solution.
A red colour
on the paper is a test for aldehyde vapour above the liquid.
* Right: The stopper
is replaced by a second one which is pierced by a pipette tip
with a tubing
leading to another vial containing water.
By heating
on an electric hot plate the acetaldehyde = ethanal is distilled.
This solution
is used for aldehyde tests with silver nitrate and with Fehling solutions.
Commercial and bead models of ethanal molecules Modelling oxygen and carbon dioxide molecules