Me20 Model
Fuel Cell with alcohol and permanganate/sulfuric acid
Due to its high cancinogen potential the use of potassium dichromate for
chemistry experiments is now forbidden.
It has to be replaced by potassium permanganate.
You have made Galvanic cells
by combining half cells made of injection bottles:
* A voltage and a current were observed
between Al and Fe
* A LED
gave light when it was connected to Pb and PbO2.
There are not only direct redox
reactions between alcohol and a mixture of permanganate and
sulfuric acid.
1. Fig. 1: Fill the left half
cell with a mixture of methylated spirit and sulfuric acid,
2. the right half cell with a permanganate
solution mixed with sulfuric acid.
3. Connect these two cells by a wick
(for flow of ions) and
the carbon electrodes
with a multimeter by two wires.
Observations
A voltage of 0.44 Volt and a current of 42.3 µA are measured (Fig.
1).
A current of 42.3 µA is flowing (Fig. 2).
Explanation
The alcohol molecules around the
negative electrode lose electrons while they are oxidized
resulting in aldehyde.
Dichromate ions around the positive
electrode take electrons while they are reduced
to Mn2+ ions.
Electrons flow through the metallic
conductors, ions move through the wick.
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modification: 18.01.2012