[k42490]

Given: an aqueous solution is 1 % NaCl by mass and has a density of 1.071 g/cm3 at 25 degrees C. The observed osmostic pressure is 7.83 atm at 25 degrees C.

What fraction of the moles of NaCl in the solution exist as ion pairs?
Calculate the freezing point that would be observed for the solution.

[IITian]

The extent of freezing-point depression can be calculated by applying Clausius-Clapeyron relation and Raoult's law together with the assumption of the non-solubility of the solute in the solid solvent. The result is that in dilute ideal solutions, the extent of freezing-point depression is directly proportional to the molal concentration of the solution.