Silver tarnishes when exposed to oxygen and dihydrogen mono sulfide, The chemical reaction is as follows: 4Ag(s) + 2H2S(g) + O2--->2Ag2S(s) + 2H2O(l) Every household has some H2S in the air (it smells like rotting eggs), but there is usually only a small quantity. H2S is almost always a limiting reaction, If a silver spoon has 0.0030 moles of tarnish on it, how many moles of H2S was it exposed to?