Re: Why does potato conduct more electricity than lemon?

Dear User,

It is not clear, from your question, what kind of conductivity test
did you conduct. Normally, if one is interested in
measuring the conductivity of a certain solution, one can use
an ohm-meter, with electrodes made of inert metal and fixed at
exactly the same distance one from another. I assume that you have measured
your conductivities consistently and that the result is not an artifact.
Now to the possible explaination :
Orange juice contains a lot of organic materials, but may contain
surprisingly little electrolites (substances capable of ionization in
solution, and, thusly, able to conduct electricity). Potato juice on the
other hand, contains mainly dissolved and partially hydrolized starch, and,
if i remember correctly, quite a lot of electrolites. There could be other
factors involved, such as for example potatoes grown with a lot of nitrate
fertilizers are known to accumulate nitrates (perfectly nice electrolites).
Simplest possible test would be to carefully evporate samples of your
juices and to subject them to high temperature. Presumably, organic
materials will burn out leaving salts intact, allowing you to measure the
amount of salts gravimetrically (by weight). Of course, as everywhere,
there are complications, linked to possible sublimation of certain salts,
the fact that juices contain a multitude of salts of organic acids (citric
in particular) which would inevitably decompose on heating and bias the
gravimetry. But first of all, mke sure that your conductivity measurements
are correct.

Hope it helps,

A.G.E.