An aqueous solution containing 16.5 g of an unknown molecular (nonelectrolyte) compound in 106.0 g of water was found to have a freezing point of -1.9 ∘c. calculate the molar mass of the unknown compound.

The molar mass of the unknown compound is 152 g/mol.

Explanation:

Depression in freezing point is given by:

= Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

= freezing point constant =

m= molality

Weight of solvent (water)= 106.0 g = 0.106 kg

Molar mass of unknown non electrolyte = M g/mol

Mass of unknown non electrolyte added = 16.5 g

Thus the molar mass of the unknown compound is 152 g/mol.

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