Colligative properties

Colligative Properties

Definition: Properties that depend on the number of solute particles in a solution, not their identity.
Key Concepts:
- Boiling Point Elevation: Presence of solutes raises the boiling point of a solution.
- Freezing Point Depression: Presence of solutes lowers the freezing point of a solution.
- Vapor Pressure Lowering: Solutes decrease the vapor pressure of the solvent.
Example Solutes: Sodium chloride (NaCl) lowers freezing point, raises boiling point.
Effect of Solute Concentration: Higher concentration results in greater colligative property changes.

Temperature Effects: Higher temperatures increase vapor pressure; the boiling point of pure water is 100^ ext{°C} at sea level.
Dissociation: Ionic compounds dissociate in solution, increasing the count of solute particles.
Examples of Dissociated Ions:
- Sodium chloride: Dissociates into Na^+ and Cl^-.
- Calcium chloride: Dissociates into Ca^{2+} and 2Cl^-, affecting properties more significantly.

General Trend: Higher temperature increases solubility for most solids.
Example Data:
- Potassium Nitrate solubility increases significantly from 20.54 ext{ g/100 mL} at 10^ ext{°C} to 220 ext{ g/100 mL} at 90^ ext{°C}.
- Sodium chloride shows a less dramatic increase in solubility with temperature.
Predictions: Solubility curves indicate that various solutes behave differently as temperature changes.

Practical Use: Salt is spread on roads to lower the freezing point of water to prevent ice formation.
Antifreeze Function: Lowers both freezing and boiling points of water in car radiators.