Bisulfite

The bisulfite ion (IUPAC-recommended nomenclature: hydrogensulfite) is the ion HSO
3
. Salts containing the HSO
3
ion are also known as "sulfite lyes". Sodium bisulfite is used interchangeably with sodium metabisulfite (Na2S2O5). Sodium metabisulfite dissolves in water to give a solution of Na+HSO
3
.

Na2S2O5 + H2O → 2 Na[HSO3]