how many grams of hydrogen sulfide will react completely with 12 grams of oxygen?
2H2S + 3O2 ==> 2H2O + 2SO2
mols O2 = grams/molar mass = ?
Using the coefficients in the balanced equation, convert mols O2 to mols H2S.
Now convert mols H2S to grams. g = mols x molar mass = ?