What is sulfurous acid, and how does it relate to #SO_2#?

1 Answer
Oct 17, 2016

Answer:

#underbrace(SO_2(g))_"sulfur dioxide" + H_2O(l) rarr underbrace(H_2SO_3(aq))_"sulfurous acid"#

Explanation:

Sulfur dioxide is the acid anhydride of sulfurous acid, i.e. #H_2SO_3-=SO_2+H_2O#. While sulfurous acid can be deprotonated, often we can treat it as water saturated with sulfur dioxide, i.e. as #H_2O*SO_2# (which is of course formally #H_2SO_3#), The smell is sulfurous, but many people (including me!) find it pleasant, and antiseptic.