Sodium metabisulfite is commonly used to precipitate dissolved gold out of aqua regia and gold chloride solutions.
WIne (and beer) makers use Sodium Metabisulfite to inhibit the growth of wild yeast and bacteria in the wine. It also works well as a sanitizer for wine making equipment.
- Wild Yeast: One quarter teaspoon per five gallons of must.
- Sanitation: Two ounces to one gallon of water.
Sodium metabisulfite is a white, slightly yellowish crystaline powder with a sulfur dioxide odor (rotten eggs), dissolving easily in water
When mixed with water or a strong acid solution, sodium metabisulfite releases sulfur dioxide (SO2), a pungent, unpleasant smelling gas that can also cause breathing difficulties in some people. Released sulfur dioxide however makes the water a strong reducing agent.