Consider the following aqueous solutions: (i) 0.20 m HOCH2 CH2 OH (nonvolatile, nonelectrolyte);

step 1 In this problem, we are given four aqueous solutions and asked to determine which has the highes

Consider the following aqueous solutions: (i) 0.20 m HOCH2...

Consider the following aqueous solutions: (i) $0.20 \mathrm{m}$ $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ (nonvolatile, nonelectrolyte); (ii) $0.10 \mathrm{m}$ $\mathrm{CaCl}_{2} ;$ (iii) $0.12 \mathrm{m} \mathrm{KBr} ;$ and (iv) $0.12 \mathrm{m} \mathrm{Na}_{2} \mathrm{SO}_{4}.$ (a) Which solution has the highest boiling point? (b) Which solution has the lowest freezing point? (c) Which solution has the highest water vapor pressure?

Consider the following aqueous solutions: (i) $0.20 \mathrm{m}$ $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ (nonvolatile, nonelectrolyte); (ii) $0.10 \mathrm{m}$ $\mathrm{CaCl}_{2} ;$ (iii) $0.12 \mathrm{m} \mathrm{KBr} ;$ and (iv) $0.12 \mathrm{m} \mathrm{Na}_{2} \mathrm{SO}_{4}.$
(a) Which solution has the highest boiling point?
(b) Which solution has the lowest freezing point?
(c) Which solution has the highest water vapor pressure?

Key Concepts

Colligative Properties

Colligative properties depend solely on the number of solute particles in a solution rather than their chemical identity. They include boiling point elevation, freezing point depression, and vapor pressure lowering, all of which are used to determine how the presence of solutes affects the physical properties of solvents.

Boiling Point Elevation and Freezing Point Depression

These are specific colligative properties that describe how a solution's boiling point is raised and its freezing point is lowered compared to a pure solvent. The magnitude of these changes is proportional to the molality of the solution and the number of particles into which the solute dissociates in solution.

Vapor Pressure Lowering

This colligative property is based on Raoult’s law, which states that the vapor pressure of a solvent is decreased by the presence of a non-volatile solute. The lowering of vapor pressure is directly proportional to the mole fraction of the solute in the solution.

van't Hoff Factor

The van't Hoff factor, denoted as 'i', reflects the number of particles a solute produces in solution. It is crucial when calculating colligative properties, as electrolytes can dissociate into multiple ions, thereby having a greater effect on the physical properties of the solution compared to non-electrolyte solutes with a van't Hoff factor of one.

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