[NewCandle] Stretching (and hiding) nanosquiddies

[Keith Nagel]

Nick writes:
>What constitutes the cathode and anode in a purely chemical system?

Perhaps there is a term to better describe this; how about canode?
In this system the aluminum acts like a cathode at the points
of silver deposition and an anode at the points of dissolution.
Subsequently there is a real current of electrons flowing between those two
points on
the aluminum. One could apply a potential externally using two
aluminum electrodes rather than generating it internally with one, and
achieve the same result. It's not _quite_ the same thing,
but for most purposes can be considered so. The main difference
being that all the factors you mention come into play so the
actual total corrosion current varies over time and temp.
This is the nut of your problem with the scaling. Not enough
aluminum surface area for the weight of the material.

As it is pretty easy to do, why not stick two small hunks of aluminum in
your KI
solution and juice it with enough current to see the discoloration
of the solution, etc. Then perhaps it will be clearer what I
am ham handedly driving at. It might help to look at the pic
I just posted and consider that the tubes are identical except
for the physical surface area of the three canodes. What a difference
in the reaction rate! You've gone down by a factor of what, one thousand
times?

K.