Question

What is the molality of a water solution that contains a non-volatile solute and freezes at – 2.25 degrees Celsius? The freezing point depression constant for water, Kf, is 1.86 degrees Celsius per mole.

Answer 1

We use our handy dandy freezing point depression equation. \[\Delta T_f = K_f \times molality\]\[{(0.00^\circ C -(-2.25^\circ C))(moles) \over 1.86 ^\circ C( Kg )} = {1.21moles \over Kg}= 1.21m\]