Title: Sodium Hydrosulfite
CAS Registry Number: 7775-14-6
Additional Names: Sodium sulfoxylate; sodium dithionite
Molecular Formula: Na2O4S2
Molecular Weight: 174.11
Percent Composition: Na 26.41%, O 36.76%, S 36.83%
Line Formula: Na2S2O4
Literature 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. |