You add 0.255 g of an orange, crystalline compound whose empirical formula is #C_10H_8Fe# to 11.12 g of benzene. The boiling point of the benzene rises from 80.10 C to 80.26 C. What are the molar mass and molecular formula of the compound?
The molecular formula is
The formula for boiling point elevation is
#color(blue)(bar(ul(|color(white)(a/a) ΔT_"b" = K_"b"mcolor(white)(a/a)|)))" "#
We can rearrange the formula to get
In your problem,
Divide both sides of the equilibrium by 0.0632.
The molar mass is 363 g/mol, so the molecular mass is 363 u.
The empirical formula mass of
The molecular mass must be an integral multiple of the empirical formula mass.
The molecular formula must be twice the empirical formula.
Its molar mass is 368.03 g.