Chapter 13: Solutions and Colligative Properties

Vocabulary flashcards for solutions and colligative properties

Solubility

The amount of substance that will saturate a given amount of solvent at a given temperature; Dependent on attractive forces between solute and solvent molecules; Typical units = g/L

Miscible

Two liquids that are completely soluble in all proportions.

Immiscible

Two liquids that form two separate layers (insoluble).

Solution

Homogeneous mixture (solute + solvent).

Aqueous solution

Solution with water as the solvent.

Solute

The substance that is dissolved in a solvent to form a solution.

Solvent

The substance in which a solute dissolves to form a solution; if both components were originally in the same phase, the solvent is the component present in the greater amount; if both components were originally in different phases, the compound that does not change phase is the solvent

Saturated

Maximum mass of solute dissolved at a given temperature (additional solute will NOT dissolve); In a saturated solution, an equilibrium exists between solid solute and dissolved solute.

Unsaturated

More solute can dissolve in the solvent at a given temperature by given volume of water (additional solute WILL dissolve).

Supersaturated

A metastable compound, more solute is dissolved than SHOULD be at a given temperature (unstable, solid will “fall out”, precipitate when solution is disturbed).

Colloidal Dispersion

Particles 1-1000 nm in diameter producing a “cloudy” (turbid) appearance.

Suspensions

Particles greater than 1 μm in size, solute slowly settles.

Solvation

The clustering of solvent molecules around solute particles.

Hydration

Solvation when the solvent is H2O.

Hydrophilic

Water loving groups = OH, CHO, C=O, COOH, NH2, Cl

Hydrophobic

Nonpolar groups = C-H, C-C

Entropy

Energetic measure of disorder (randomness) of the system; ΔS is >0 (i.e. positive) for the dissolution of a solute by a solvent.

Spontaneous process

Occurs without outside intervention; Measured with ΔG (Gibbs Free Energy); At constant T & P, a process is spontaneous if ΔG < 0 (negative).

Molarity (M)

moles of solute / Liters of solution

Molality (m)

moles of solute / mass of solvent (kg); Important: Molality is not temperature dependent and that’s why we use molality for boiling point elevation and freezing point depression

Mass Percent

(mass of component A / mass of solution) * 100%

Mole Fraction (XA)

nA / (nA + nB + …)

Parts per million (ppm)

(mass of solute / mass of solution) * 10^6

Parts per billion (ppb)

(mass of solute / mass of solution) * 10^9