From: utzoo!decvax!harpo!eagle!mhuxt!mhuxj!mhuxi!mhuxv!pdt
Newsgroups: net.cooks
Title: sulfite vs. bisulfite
Article-I.D.: mhuxv.8
Posted: Thu Mar 24 09:36:36 1983
Received: Fri Mar 25 09:05:09 1983

One minor correction to the minor correction given on sulfites and
bisulfites:  which one you have and in what proportion to the
other one depends only on the acidity (pH) of the solution in which
the sulfite or bisulfite is dissolved.  Sulfurous acid is a weak
acid, so dissolving a sulfite salt in water produces both sulfite
and bisulfite ions.  Bisulfite itself is weakly amphoteric (i.e. can
be both an acid and a base, but weakly so);  a solution of a
bisulfite salt thus has bisulfite, sulfite, and sulfurous acid
(sulfur dioxide plus water).  Addition of acid to either of these
solutions makes a higher proportion of bisulfite and sulfurous
acid; addition of base makes a higher proportion of sulfite.