Nomenclature
CAS number: 7775-14-6
Sodium sulfoxylate; sodium dithionite.
Na
2O
4S
2; mol wt 174.11.
Na 26.41%, O 36.76%, S 36.83%.
Na
2S
2O
4.
Description and references
The hydrosulfite of commerce contains 85-90%
Na2S2O4.
Properties
White or grayish-white, cryst powder; slight characteristic
odor. Oxidizes in air (more readily so in presence of moisture or
when in soln) to bisulfite and bisulfate and acquires an acid reaction.
Very sol in water, slightly in alcohol.Note
The name sodium hydrosulfite is applied
also to NaHSO2, mol wt 88.06, sol in water, alcohol. Still
more confusion results when “sodium hyposulfite” is applied to this
compd (Na2S2O4) see 1957
Subject Index to Chem. Abstracts, p 2218s under sodium dithionite.Use
As reducing agent, particularly in dyeing with indigo
and vat dyes; bleaching soaps, straw; removing dyes from dyed fabrics.