Reduction of hydrogen sulfide by silver Why can $\ce{H2S}$ be reduced by $\ce{Ag}$ when left in air:
$$\ce{2 Ag + H2S -&gt; Ag2S + H2}$$
If silver is a noble metal that should not reduce hydrogen?
Check the electronegativity of hydrogen, silver and noble metals. In addition, though, consider that the product, $\ce{Ag2S}$, is a solid. The reaction is driven in one direction by precipitation, continually removing sulfur from the air.