Question #79600

1 Answer
Apr 11, 2016

Sulphur dioxide gas reacts with hydrogen sulphide to give rise to sulphur and water, not oxygen.


A little drop of water activates the reaction between the two gases.

#SO_2(g) + H_2S(g) -> S(s) + H_2O(l)#

Despite it is a redox, the equation can be easily balanced by trials and errors.
Having two oxygen atoms in the reactants, we need four hydrogen atoms, that is two #H_2S# molecules, and we obtain three suphur atoms together with two water molecules:

#SO_2(g) + 2H_2S(g) -> 3S(s) + 2H_2O(l)#

Taking in account that sulphur is octaatomic and the least common multiple between 3 and 8 is 24, we must multiply every coefficient by eight to have the very complete equation:

#8SO_2(g) + 16H_2S(g) -> 3S_8(s) +16 H_2O(l)#