•In a 32.0-g sample of hydrazine, there are 28.0 g N and 4.0 g H. The
molar mass is 32.0 g/mol. What is the molecular formula?
•1) find emp formula
–28.0 g N è 2.0 mol N
–4.0 g H è 4.0 mol H
–Emp formula = NH2
•2) find molar mass ratios
–molar mass (32.0) / emp mass ( 16.0) = 2
•3) multiply by 2 to get formula = N2H4