All hydrogen sulfide (H2S) contained in 4.00 g of crude oil is removed by distillation and collected in a CdCl2 solution. The precipitate of CdS is then filtered, washed and converted into CdSO4 by calcination. If 0.1236g of CdSO4 is recovered, what is the percentage mass of H2S in the original sample of crude oil? Write and balance all reactions.