Solutions, Mixtures, and Colligative Properties: Key Concepts and Formulas

Unsaturated Solution

Contains less than the maximum amount of solute that can be dissolved at a given temperature.

Saturated Solution

Contains the maximum amount of dissolved solute.

Supersaturated Solution

Contains more dissolved solute than is normally possible at that temperature.

Homogeneous Mixture (Solution)

Uniform throughout, component particles are atomic or molecular in size (nm).

Heterogeneous Mixture (Suspension/General)

Not uniform throughout, with visible particles that settle on standing.

Suspension

A heterogeneous mixture with large particles that can be seen by the naked eye and settle out over time.

Solvation

The general process of solvent molecules surrounding solute particles.

Hydration

The specific term used when the solvent is water.

Miscible

Two liquids that can mix in any proportion to form a solution.

Immiscible

Two liquids that do not mix and instead form separate layers.

Colligative Properties

Properties that depend only on the number of solute particles, not their identity.

Vapor Pressure Lowering

Adding a non-volatile solute lowers the vapor pressure of the solvent.

Boiling Point Elevation (BPE)

Solutions boil at a higher temperature than the pure solvent.

Freezing Point Depression (FPD)

Solutions freeze at a lower temperature than the pure solvent.

Osmotic Pressure

Increases with higher solute concentration.

Agitating (Stirring)

Brings fresh solvent into contact with the solute.

Increasing Surface Area

Crushing the solute into smaller pieces (powder).

Increasing Temperature

Increases kinetic energy, causing more frequent and forceful collisions.

"Like Dissolves Like"

Polar solvents dissolve polar solutes and ionic solutes; nonpolar solvents dissolve nonpolar solutes.

Solubility Curve Interpretation

On the line: saturated; below the line: unsaturated; above the line: supersaturated.

Molarity

M = moles of solute/liters of solution.

Molality

m = moles of solute/kg of solvent.

Dilution Formula

M1V1 = M2V2.

BPE Formula

▵Tb = i x Kb x m.

FPD Formula

▵Tf = i x Kf x m.

Kb

0.51 degrees C.

Kf

1.86 degrees C.