Re: [RML] pH & email addy

HH (Harro.Hieronimus at t-online.de)
Fri, 26 Mar 1999 18:44:59 +0100

Mach T. Fukada schrieb:
> I think they are arguing about the theoretical pH of pure water (as Wright
> indicated distilled/deionized is not really pure). Assuming Water
> dissassociates into H+ OH- but not to a high degree one would expect that
> there would be a measurable amount of Hydorgen Ions and hence a slightly
> acidic pH. Need to find the dissassociation constant for water to
> determine the theoretical concentration of Hydorgen ions.
>

Pure water (as double destilled water also) has a pH of 7 as H+ and OH- iones
are in an equilibrum. Technically it is easy to produce this water, however,
without air contact (e.g. under nitrogen atmosphere). As soon as you have
contact with air some CO2 will be dissolved and the pH sinks - as to Brown's
molecular movement rules without any chance to influence or avoid it - to about
5.5

Best regards

Harro Hieronimus, Solingen, Germany
harro.hieronimus at t-online.de

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