Re: Why does electrostatic attraction in water decrease?

[hERBERT H GOTTLIEB <herbgottlieb@JUNO.COM>]

It seems as if  the author, Pentcho
 Valev has some difficulty with the
English language but it would be helpful if someone could help
translating his equations below.

Herb


On Mon, 22 Apr 2002 17:42:32 +0200 Pentcho Valev <pvalev@BAS.BG> writes:
> Let us assume that a constant-charge parallel-plate capacitor with
> vertical plates is suspended over a pull of water. The magnitude of
> the
> force of attraction beween the plates is F. Then the capacitor is let
> down and immersed in the pull - the force of attraction is greatly
> reduced and becomes F/80. What can be the molecular mechanism behind
> that? The situation in water can be illustrated by the following
> picture:
>
> +P (-)(+) (-)(+) (-)(+)........(-)(+) P-
>
> where +P and P- are the positive and negative plates and (-)(+) are
> water dipoles. If there were no thermal motion, the force of
> attraction
> would slightly increase, due to polarization of water. So, in my
> view,
> the radical decrease in attraction can only be due to thermal motion.
> For instance, thermal motion can force the second dipole on the left
> to
> rotate:
>
> +P (-)(+) (+)(-) (-)(+)........(-)(+) P-
>
> Clearly, the rotation results in a local electrostatic "push", and
> the
> sum of all such "pushes" amounts to a kind of thermal pressure acting
> against the force of attraction. If this pressure does exist, it
> would
> be NON-CONSERVTIVE - as the plates are drawn apart in water, the
> pressure will do work at the expense of heat absorbed (somewhat
> analogous to work a gas does on expansion).
> The explanation is perhaps too strange but for the moment I don't see
> a
> more reasonable molecular mechanism. Any other explanation is
> welcome.
>
> Pentcho Valev