[alt-photo] Re: "Expired" dichromate

[Tomas Sobota]

Judy, I don't know much about the deep sea demon, to be sure, but common
salt concentration in seawater is pretty restricted in range at between 31
and 38 parts in a thousand worldwide.  But the actual concentration value is
not an issue here, just the fact that  "...the more a chemical is diluted
the less well it keeps..." is obviously not true considering that this low
concentration has not changed too much in a billion years.

Actually, for a chemical in solution, diluted or not, to degrade with time
there has to be also a (photo)chemical reaction going on, as for example if
there are organic impurities in a dichromate solution. Mere dilution has no
effect on how well a chemical keeps, and my example of seawater is as good a
proof as any.

Tom Sobota


On Mon, May 3, 2010 at 4:01 AM, Judy Seigel <jseigel at panix.com> wrote:

> Trying to cut back on the 20 thousand messages in my incoming file, I'm
> deleting deleting deleting... but a couple need comments.  I forget what
> intimate family member admonished me, "you can't correct the world," but my
> reply then was, "I can at least try."  Sometimes, however, it's easy:
>
> I wrote", "As I understand it, the more a chemical is diluted the less well
> it keeps..."
>
> And on Thu, 29 Apr 2010, Tomas Sobota remarked:
>
>
>  By that you would say that Sodium chloride does not keep well in seawater
>> ?
>>
>
> I have no idea -- nor do you:  "Seawater" is not a constant, any more than
> "person" or "earth" or even "air" is a constant, so how sodium chloride
> (pure or not) keeps in it has so many variables as to defy precision, not to
> mention that it may originate with the deep sea demon whose supply comes
> from the bowels of the earth and varies with the year, month, day,
> temperature, elevation, location, and her mood of the moment.
>
>
> J.
>
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