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.

Verified step by step guidance

1. Identify the components of the solution: a nonvolatile solute and a liquid solvent.
2. Understand the process of freezing: as the solution cools, the solvent molecules begin to form a solid structure (crystal lattice).
3. Consider the nature of the solute: since it is nonvolatile, it does not easily escape into the vapor phase and remains in the solution.
4. Recognize that during freezing, the solvent molecules preferentially form the solid phase, while the solute remains in the liquid phase or is excluded from the crystal lattice.
5. Conclude that the solid that forms as the solution freezes is nearly pure solvent, not solute, because the solute is typically excluded from the solid crystal lattice of the solvent.

Key Concepts

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 these properties is essential for predicting how a solute will affect the physical characteristics of a solvent.

Freezing Point Depression

Freezing point depression occurs when a solute is added to a solvent, resulting in a lower freezing point than that of the pure solvent. This phenomenon is a direct consequence of colligative properties, where the presence of solute particles disrupts the formation of the solid structure of the solvent, requiring a lower temperature to achieve freezing. This concept is crucial for understanding the behavior of solutions at low temperatures.

Purity of Crystals

When a solution freezes, the solid that forms is typically composed of the solvent in a crystalline structure, while the solute remains dissolved in the liquid phase. As a result, the solid that forms is nearly pure solvent, not solute. This principle is important in crystallization processes and helps explain why the statement about the solid being nearly pure solute is false.