<P> Sodium metabisulfite releases sulfur dioxide in contact with strong acids: </P> <Dl> <Dd> Na S O + 2 HCl → 2 NaCl + H O + 2 SO </Dd> </Dl> <Dd> Na S O + 2 HCl → 2 NaCl + H O + 2 SO </Dd> <P> On heating to high temperature, it releases sulfur dioxide, leaving sodium sulfite behind: </P>

What is the oxidation number of s in sodium metabisulfite na2s2o5