pdt (03/24/83)
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.