Boiling point elevation constant

Definition

The boiling point elevation constant, denoted as $K_b$, is a proportionality constant used to quantify the increase in boiling point of a solvent when a solute is added. It has units of degrees Celsius per molal ($\text{°C/m}$).

5 Must Know Facts For Your Next Test

1. $K_b$ is specific to each solvent and must be determined experimentally.
2. The boiling point elevation can be calculated using the formula $\Delta T_b = K_b \cdot m$, where $m$ is the molality of the solution.
3. Boiling point elevation is a colligative property, meaning it depends on the number of solute particles, not their identity.
4. $K_b$ values for common solvents like water are often provided in textbooks or reference materials.
5. Boiling point elevation occurs because the addition of a non-volatile solute lowers the vapor pressure of the solution.

Related terms

Molality:

A measure of solute concentration defined as moles of solute per kilogram of solvent.

Colligative Properties:

Properties that depend on the number of solute particles in a solution, such as boiling point elevation and freezing point depression.

Vapor Pressure: The pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature.