Question

The formula for mustard gas used in chemical warfare is c4h8scl2 (159.09 g/mol). what is the percentage of hydrogen in the compound?

Answer 1

The molecular formula for mustard gas is C₄H₈SCl₂
the molecular mass of mustard gas - 159.09 g/mol
atomic mass of H is 1 g/mol
The mass of H in 1 mol of compound - 1 x 8 = 8 g
this means that in 159.09 g of compound , 8 g of H present 
mass percentage of hydrogen = 8 g/ 159.09 g x 100% 
mass percentage of hydrogen = 5.03%