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Ch.13 - Properties of Solutions
All textbooksBrown 15th EditionCh.13 - Properties of SolutionsProblem 64b
Chapter 13, Problem 64b

You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false.
b. The freezing point of the solution is independent of the concentration of the solute.

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1
Understand the concept of freezing point depression: When a nonvolatile solute is added to a solvent, the freezing point of the solution is lowered compared to the pure solvent.
Recall the formula for freezing point depression: \( \Delta T_f = i \cdot K_f \cdot m \), where \( \Delta T_f \) is the change in freezing point, \( i \) is the van't Hoff factor, \( K_f \) is the freezing point depression constant, and \( m \) is the molality of the solution.
Note that the formula shows \( \Delta T_f \) is directly proportional to the molality \( m \), which is a measure of the concentration of the solute.
Conclude that since \( \Delta T_f \) depends on \( m \), the freezing point of the solution is indeed dependent on the concentration of the solute.
Therefore, the statement 'The freezing point of the solution is independent of the concentration of the solute' is false.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Colligative Properties

Colligative properties are properties of solutions that depend on the number of solute particles in a given amount of solvent, rather than the identity of the solute. These properties include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. Understanding colligative properties is essential for predicting how the addition of a solute affects the physical properties of a solvent.
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Colligative Properties

Freezing Point Depression

Freezing point depression is a colligative property that describes how the freezing point of a solvent decreases when a nonvolatile solute is added. The extent of this depression is directly proportional to the concentration of the solute particles in the solution. This means that as the concentration of the solute increases, the freezing point of the solution becomes lower, contradicting the statement in the question.
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Freezing Point Depression

Nonvolatile Solute

A nonvolatile solute is a substance that does not readily evaporate and has a negligible vapor pressure compared to the solvent. When a nonvolatile solute is dissolved in a solvent, it affects the solvent's physical properties, such as lowering its vapor pressure and freezing point. This characteristic is crucial for understanding how solutes influence the behavior of solutions in various chemical contexts.
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Solution Components
Related Practice
Textbook Question

Assume that a portable reverse-osmosis apparatus operates on seawater, whose effective concentration (the concentration of dissolved ions) is 1.12 M, and that the desalinated water output has an effective molarity of about 0.02 M. What minimum pressure must be applied by hand pumping at 297 K to cause reverse osmosis to occur?

Textbook Question

You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false.

a. The solid that forms as the solution freezes is nearly pure solute.

Textbook Question

a. The vapor pressure of pure water at 60°C is 149 torr. What vapor pressure is predicted by Raoult’s law for a solution at 60°C that is 50 mol% water and 50 mol% ethylene glycol (a nonvolatile solute)?