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From: jbs@mit-eddie.UUCP (Jeff Siegal)
Newsgroups: net.sci
Subject: Re: Question about Electricity
Message-ID: <333@mit-eddie.UUCP>
Date: Thu, 7-Nov-85 00:57:21 EST
Article-I.D.: mit-eddi.333
Posted: Thu Nov  7 00:57:21 1985
Date-Received: Fri, 8-Nov-85 21:23:31 EST
References: <621@hlwpc.UUCP> <662@petrus.UUCP> <714@alberta.UUCP> <2358@ukma.UUCP>
Reply-To: jbs@mit-eddie.UUCP (Jeff Siegal)
Distribution: net
Organization: MIT, Cambridge, MA
Lines: 18
Keywords: water, electricity

In article <2358@ukma.UUCP> slg@ukma.UUCP (Sean Gilley) writes:
>
>
>     Pure water (H2O) does not conduct electricity.  The reason you need to
>be careful with electricity around water is that the minerals in solution
>within the water are conductors.
>
>

This is not quite correct.  Pure water (H2O) DOES conduct elecricity.
However, the conductivity is sufficiently low that it can often be
ignored.  What causes aqueous solutions to be conductive is the ions
which present in the solution.  If I remember correctly, water is itself
partially ionized.  The concentration of H+ (and other complexes, H3O+,
etc.) is 1 x 10**-7 mole/L.  The pH is defined as - LOG10(concentration 
of H+ ions).  Thus the pH of pure water is 7.

Jeff Siegal - MIT EECS (jbs@mit-eddie)