Question

Part A - Calculation of Boiling-Point Elevation and Freezing-Point Depression Which aqueous solution will have the lowest freezing point? Which aqueous solution will have the lowest freezing point? a) 0.10 m HCl b) 0.15 m NaCl c) 0.050 m CaCl2 d) 0.20 m C12H22O11 e) 0.050 m CH3COOH

Answer 1

Colligative property is directly proportional to molality or concentration. More the concentration more will be the elevation in boiling point or depreesion in freezing point.

Also colligative property depends on the number of particles as well.

the dicreasing order of freezing point depression as follows:

0.15 m NaCl > 0.20 mC12H22O11 =0.10 m HCl > 0.050 m CaCl2 > 0.050 m CH3COOH

Thus, 15 m NaCl will have the lowest freezing point.

[Note: 0.15 m NaCl = 0.30 m particle concentration (NaCl dissociate into two ions)

           0.20 m C12H22O11 = 0.20 m particle concentration (no dissociation of this molecule)

            0.10 m HCl = 0.20 m particle concentration(HCl dissociate into two ions)

            0.05 m CaCl2 = 0.15 m particle concentration (CaCl dissociate into 3 ions)

            0.05 m CH3COOH = 0.10 m particle concentration (CH3COOH dissociate into two ions)