Title:  Potassium Metabisulfite 
CAS Registry Number:  16731-55-8 
CAS Name:  Potassium pyrosulfite 
Molecular Formula:  K2O5S2 
Molecular Weight:  222.32 
Percent Composition:  K 35.17%, O 35.98%, S 28.85% 
Line Formula:  K2S2O5 
Literature References:  The article of commerce contains ~95% K2S2O5. 
Properties:  White crystals or cryst powder; sulfur dioxide odor; acid reaction; liberates SO2 with acids; oxidizes in air to sulfate, more readily in presence of moisture.  It may catch fire if much heat develops in powdering it.  Freely sol in water; insol in alcohol.  Keep dry and well closed. 
Use:  As antifermentative in breweries and wineries; bleaching straw; preservative for fruits and vegetables.   |