Excess Reagent

4 H##_2## (g) + CS##_2## (g) ##\longrightarrow## CH##_4## + 2 H##_2##S (g)
Methane and hydrogen sulfide form when hydrogen reacts with carbon disulfide. Identify the excess reagent and calculate the remaining mass after 36 L of H##_2## reacts with 12 L of CS##_2##