Solutions, Colligative Properties, and Colloids – Core Vocabulary

These vocabulary flashcards cover the major concepts from the lecture on solutions, colligative properties, and colloids, providing concise definitions for key terms students need to master.

Solution

A spontaneous homogeneous mixture of two or more substances whose composition is uniform throughout and whose phase is usually that of the solvent.

Solute

The substance present in the smaller amount(s) in a solution; it is dissolved by the solvent.

Solvent

The component present in the larger amount in a solution; it determines the solution’s physical state.

Gas-in-Gas Solution

A solution where both solute and solvent are gases, e.g., O₂ in N₂ (air).

Gas-in-Liquid Solution

A solution with a gaseous solute and liquid solvent, e.g., O₂ in seawater.

Solid-in-Liquid Solution

A solution with a solid solute dissolved in a liquid solvent, e.g., NaCl in water.

Solid-in-Solid Solution

A homogeneous alloy such as Zn in Cu (brass).

Homogeneous Mixture

A mixture whose components are uniformly distributed so that any small sample has the same composition as the whole.

Heterogeneous Mixture

A mixture in which components are not uniformly distributed; different regions have different compositions.

Characteristics of Solutions

homogeneous composition, same phase as solvent, solute evenly mixed, no settling, variable concentration within solubility limits.

Saturated Solution

Contains the maximum amount of solute that can dissolve at a specific temperature.

Unsaturated Solution

Contains less solute than a saturated solution at the same temperature.

Supersaturated Solution

Contains more solute than the equilibrium solubility; unstable and precipitates upon seeding or agitation.

Solubility

Maximum concentration of a solute that can dissolve in a given solvent at a fixed temperature and pressure (g solute / L solution).

Solvation

Process in which solute particles are surrounded by solvent molecules; called hydration when the solvent is water.

ΔHsoln (Enthalpy of Solution)

Overall heat change when a solution forms; sum of solvent–solvent (ΔH1), solute–solute (ΔH2), and solute–solvent (ΔH3) interactions.

Ideal Solution

A solution for which ΔHsoln ≈ 0 because intermolecular forces between all species are similar; mixing is driven purely by entropy.

“Like Dissolves Like”

Guideline stating substances with similar intermolecular forces (polarity) are mutually soluble.

Henry’s Law

Cg = kPg; the solubility of a gas in a liquid is directly proportional to its partial pressure above the liquid.

Miscible Liquids

Two liquids that mix in all proportions (e.g., ethanol and water).

Immiscible Liquids

Liquids that do not mix appreciably (e.g., oil and water).

Partially Miscible Liquids

Liquids with limited mutual solubility (e.g., bromine and water).

Electrolyte

A substance that produces ions in solution, enabling it to conduct electricity.

Nonelectrolyte

A substance that dissolves without producing ions; its solutions do not conduct electricity.

Strong Electrolyte

Substance that dissociates ~100 % into ions in solution (e.g., NaCl, HCl).

Weak Electrolyte

Substance that produces only a small fraction of ions in solution (e.g., acetic acid).

Ion–Dipole Attraction

Electrostatic attraction between an ion and a polar molecule; key force in dissolving ionic compounds in polar solvents.

Dissociation

Breaking apart of an ionic compound into ions when it dissolves.

Molarity (M)

Moles of solute per liter of solution; temperature-dependent.

Molality (m)

Moles of solute per kilogram of solvent; temperature-independent.

Mass Percent

100 × (mass of solute ÷ mass of solution).

Mole Fraction (X)

Moles of a component divided by total moles of all components in the mixture.

Colligative Property

A property that depends only on the number of solute particles, not their identity (e.g., ΔP, ΔTb, ΔTf, π).

Vapor Pressure Lowering (ΔP)

Decrease in solvent vapor pressure when a nonvolatile solute is added.

Raoult’s Law

Psolution = Xsolvent P*solvent; relates vapor pressure of an ideal solution to solvent mole fraction.

Boiling Point Elevation (ΔTb)

Increase in boiling point of a solvent when a solute is added; ΔTb = i kb m.

Freezing Point Depression (ΔTf)

Decrease in freezing point of a solvent upon adding solute; ΔTf = i kf m.

Semipermeable Membrane

Material that allows certain molecules (usually solvent) to pass while blocking others (solute).

Osmosis

Net flow of solvent through a semipermeable membrane from pure solvent to a solution.

Osmotic Pressure (π)

Pressure required to stop osmosis; π = iMRT.

Reverse Osmosis

Process in which pressure greater than π forces solvent from a solution into pure solvent; used in water purification.

van’t Hoff Factor (i)

Number of particles the solute yields in solution; corrects colligative property equations for electrolytes.

Ion Pair

A loosely associated cation–anion pair in solution that reduces the effective number of independent ions.

Colloid

Dispersion of particles (1–1000 nm) of one phase throughout another; intermediate between solution and suspension.

Tyndall Effect

Scattering of light by colloidal particles, making a beam visible.

Aerosol (Colloid)

Colloid with gas as the dispersing medium and liquid or solid dispersed phase (e.g., fog, smoke).

Emulsion

Liquid droplets dispersed in a liquid medium (e.g., mayonnaise).

Sol (Colloid)

Solid particles dispersed in a liquid (e.g., milk of magnesia).

Gel

Liquid dispersed in a solid network (e.g., jelly, butter).

Hydrophilic Colloid

Water-loving colloid stabilized by attraction between dispersed particles and water.

Hydrophobic Colloid

Water-fearing colloid stabilized by surface charges or adsorbed ions repelling each other.