Solutions & Colligative Properties

Ideal Solution

A solution in which the interactions between unlike molecules are identical to those between like molecules, so Raoult's law holds at all…

ΔH_mix = 0, ΔV_mix = 0 Dimensionless

Immiscible Liquids

Two liquids that do not dissolve in one another and separate into distinct layers.

Dimensionless

Solutions & Colligative Properties

Isotonic Solution

A solution having the same osmotic pressure as another, so that no net osmotic flow occurs between them.

π₁ = π₂ atm

Solutions & Colligative Properties

Like Dissolves Like

The empirical rule that substances dissolve best in solvents with similar polarity and bonding character.

Dimensionless

Solutions & Colligative Properties

Mass Percentage

The mass of solute expressed as a percentage of the total mass of the solution.

% w/w = (m_solute / m_solution) × 100 Dimensionless

Solutions & Colligative Properties

Micelle

A spherical aggregate of surfactant molecules that forms in solution above a characteristic concentration.

mol/L

Solutions & Colligative Properties

Miscibility

The ability of two liquids to mix in all proportions to form a single homogeneous phase.

Dimensionless

Solutions & Colligative Properties

Molality

The concentration of a solution expressed as moles of solute per kilogram of solvent.

m = n / mass of solvent (kg) mol/kg

Solutions & Colligative Properties

Molarity

The concentration of a solution expressed as moles of solute per litre of solution.

M = n / V M (mol/L)

Solutions & Colligative Properties

Mole Fraction

The ratio of the moles of one component to the total moles of all components in a mixture.

x_A = n_A / n_total Dimensionless

Solutions & Colligative Properties

Negative Deviation

Behaviour in which a solution exerts a lower vapour pressure than Raoult's law predicts.

p < x p° Pa

Solutions & Colligative Properties

Non-Ideal Solution

A solution that departs from Raoult's law because interactions between unlike molecules differ from those between like molecules.

p ≠ x p° Pa

Solutions & Colligative Properties

Normality

The concentration of a solution expressed as gram equivalents of solute per litre of solution.

N = M × n-factor N (equiv/L)

Solutions & Colligative Properties

Osmosis

The net movement of solvent molecules through a semipermeable membrane from a dilute to a concentrated solution.

Dimensionless

Solutions & Colligative Properties

Osmotic Pressure

The external pressure that must be applied to a solution to prevent the inward flow of solvent through a semipermeable membrane.

π = i M R T atm

Solutions & Colligative Properties

Parts per Billion

A concentration unit expressing one part of solute per thousand million parts of solution.

ppb = (m_solute / m_solution) × 10⁹ ppb

Solutions & Colligative Properties

Parts per Million

A concentration unit expressing one part of solute per million parts of solution by mass or volume.

ppm = (m_solute / m_solution) × 10⁶ ppm

Solutions & Colligative Properties

Positive Deviation

Behaviour in which a solution exerts a higher vapour pressure than Raoult's law predicts.

p > x p° Pa

Solutions & Colligative Properties

Raoult's Law

The partial vapour pressure of each component of an ideal solution equals its mole fraction times its pure vapour pressure.

p_A = x_A p°_A Pa

Solutions & Colligative Properties

Relative Lowering of Vapour Pressure

The fractional reduction in a solvent's vapour pressure caused by dissolving a non-volatile solute.

(p° − p) / p° = x_solute Dimensionless

Solutions & Colligative Properties

Reverse Osmosis

The forced flow of solvent from a concentrated to a dilute solution by applying pressure greater than the osmotic pressure.

p_applied > π atm

Solutions & Colligative Properties

Saturated Solution

A solution in dynamic equilibrium with undissolved solute, containing the maximum amount that will dissolve at that temperature.

rate dissolve = rate crystallise mol/L

Solutions & Colligative Properties

Semipermeable Membrane

A barrier that allows solvent molecules to pass while blocking larger solute particles.

Dimensionless

Solutions & Colligative Properties

Sol

A colloidal system consisting of solid particles dispersed throughout a liquid medium.

nm