"Custos Custodum" wrote in message
...
On Tue, 1 Feb 2005 22:00:22 -0000, "Brian Reay"
wrote:

"Reg Edwards" wrote in message
...

It later transpired in the laboratory that when water is under
relatively
high pressure, such as at the bottom of the North Sea, when in contact
with
a thick polyethylene membrane it dissasociates into hydrogen and
oxygen.

The very light element diffuses through leaving heavy oxygen on the
outside.
Thus, after a few years, the air-space on the inside becomes filled
with
high pressure hydrogen.

What caused this "disassociation", and where did it happen?

Water dissociates naturally to a small extent. Think of how the pH
scale is derived.

I thought the pH scale came from "per Hydronium"- H30+ ?

If the 'extra' H came from the water, then there would also be OH- to
neutralise it.


Just, I'd expect
the hydrogen to bubble off PDQ, assuming this process did occur. Also,
diffusion is the movement of something from a high to a low
concentration,
assuming the mechanism is correct, I wonder how long before the
concentration would equalise (after all, the hydrogen around the cable
must
have been in pretty low concentration.

It all sounds a bit like Maxwell's 'demons' but my half-educated guess
is that the polyethylene was acting as a semi-permeable membrane,

Semi-permeable membranes feature in osmosis, rather than diffusion (although
I have heard osmosis related to diffusion in via the concept of the solvent
diffusing ).

allowing only the much smaller hydrogen atoms (ions?) to pass through
under the action of the pressure differential.

As I recall, a hydrogen ion doesn't stay 'free' for long.

Long time since I did Chemistry, is Dr Boris not about?
--
Brian Reay
www.g8osn.org.uk
www.amateurradiotraining.org.uk
FP#898