Question

A certain organic substance used as a solvent in many reactions contains carbon, hydrogen, oxygen and sulphur. Weight % of hydrogen in the compound is 7.7. The weight ratio C : O : S = 3 : 2 : 4. What is the least possible molar mass (in g) of the compound ?

Answer 1

Let us suppose that the mass of the compound is $100$ g

Mass % of H=$7.7$

Mass % of C=$30.74$

Mass % of O=$20.52$

Mass % of S=$41.04$

least possible molar mass of the compound is the empirical molar mass

empirical formula=$C_2{H}_{6}OS$

=$2\left(c\right)+6\left(H\right)+\left(O\right)+S$=$24+6+16+32$=$78$ g