Boiling Point Elevation - Vocabulary

Vocabulary flashcards covering key concepts and terms from the Boiling Point Elevation lecture notes.

Boiling Point Elevation

The rise in a solvent's boiling point when a solute is dissolved, a colligative property depending on the number of dissolved particles.

Colligative Property

A property that depends on the number of solute particles in solution rather than their identity; examples include boiling point elevation, freezing point depression, and vapor pressure lowering.

Van’t Hoff Factor (i)

The number of particles produced in solution from a solute; indicates dissociation (e.g., NaCl → 2 ions, sugar → 1).

Molality (m)

The concentration unit equal to moles of solute per kilogram of solvent.

ΔTb

The boiling point elevation, calculated as ΔTb = Tb(solution) − Tb(solvent).

ebullioscopic constant (kb)

A solvent-specific constant used in boiling point elevation calculations; ΔTb = i · kb · m.

Dissociation (in solution)

The process by which a compound separates into ions in solution, affecting the number of particles and the Van’t Hoff factor.

NaCl dissociation in water

Sodium chloride dissociates into Na+ and Cl− ions in water, increasing the particle count and i.

Sugar (sucrose) in water dissociation

Sucrose does not dissociate into ions in water, so i ≈ 1.

Observed Molality

The molality calculated from experimental data using ΔTb and i (m = ΔTb / (i · kb)).

Theoretical Molality

Molality calculated from known masses: m = mol solute / kg solvent (convert grams to moles before dividing by kg solvent).

Boiling Point of Water (reference)

Pure water boils at 100°C at 1 atm, used as the reference point for boiling point elevation calculations.