Re: Sodium Bisulfite

From: Alberto Novo ^lt;[email protected]>
Date: 10/07/04-11:53:29 PM Z
Message-id: <20041008055329.1152.qmail@webmail.aruba.it>

Katharine Thayer wrote:

> .... and if
> it's basic chemistry, why not just spell it out simply, explain how it
> works differently for sulfite vs bisulfite and metabisulfite.

Solutions od sulphite (Na2SO3) are alkaline. From the chemical information
you should have seen the pH value: 11 for a 20% solution.
Chromium(III) salts behave more or less as iron(III) salts: in neutral or
alkaline solutions they form the insoluble tri-hydrate Me(OH)3 (Me is the
metal).
Solutions of bisulphite or metabisulphite (no matter which is the
countercation) are all acidic, see for example -ever looking at the pH
values-:
www.basf.de/basf/img/produkte/schwefel/CAA-NBSLFG-E-REV7.pdf
www.chemicalland21.com/arokorhi/industrialchem/inorganic/Sodium%20metabisulf
ite.htm
Both sulphite and bisulphite are able to reduce Cr(IV) to Cr(III), but only
the latter has the capability to keep some reduced chromium in solution due
to its acidity.
Chromium hydrate and oxide-hydrates are all greenish.

Alberto
Received on Thu Oct 7 23:53:43 2004

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