A1.450 g sample of an unknown organic compound , x, is dissolved in 15.0 g of toluene
( c7h8 = 92 g/mol) and the freezing point is lowered by 1.33 oc. what is the molecular weight
of the organic compound? (kf = 5.12 oc/m).

Molecular weight of the compound = 372.13 g/mol

Explanation:

Depression in freezing point is related with molality of the solution as:

Where,

= Depression in freezing point

= Molal depression constant

m = Molality

m = 0.26

Molality =

Mass of solvent (toluene) = 15.0 g = 0.015 kg

Moles of compound = 0.015 × 0.26 = 0.00389 mol

Mass of the compound = 1.450 g

Molecular weight =