posted by tony .
1.00 g zinc and 0.80 g sulfur are allowed to react all the zinc is used up 1.50 g of zinc sulfide is formed and some unreacted sulfur remains what is the mass of unreacted sulfur
Zn + S ==> ZnS
mols Zn = 1.00/65.39 = 0.016 but you need to do it more accurately.
Convert mols Zn to mols S. That's 0.016 mols Zn x (1 mol S/1 mol Zn) = 0.016 mols Zn x 1/1 = 0.016 mols S.
grams S used = mols x atomic mass S; then
g S initially - g S used = g S remaining after the reaction.