Solutions and Colligative Properties

Comprehensive vocabulary flashcards covering the classification of mixtures, solution processes, factors affecting solubility, concentration units, and colligative properties.

Heterogeneous Mixture

A combination of two or more substances that do not combine chemically and consist of visibly different substances or phases (solid, liquid, gas).

Homogeneous Mixture

A combination of substances that maintains the same uniform appearance and composition throughout, existing in a single phase; commonly referred to as a solution.

Suspension

A special type of heterogeneous mixture containing larger particles that are filterable and eventually settle out over time.

Colloid

A mixture that appears homogeneous to the naked eye but contains larger particles than a true solution that do not settle and cannot be separated by filtration (such as fog, smoke, or mayonnaise).

Solute

The substance that is dissolved to make a solution, which separates into individual particles and is typically present in the smaller amount.

Solvent

The substance in a solution that dissolves the solute, typically present in the greater amount.

Alloy

A solid homogeneous mixture composed of one or more metals and one or more other elements, produced through melting and mixing (such as brass, bronze, and stainless steel).

Solvation

The process by which solvent molecules attract, pull apart, and surround individual solute particles as a solution forms.

Dissolution

A physical process in which a solute disperses into a solvent to form a solution, characterized by the ability to recover the original solute by evaporating the solvent.

Solubility

The maximum amount of solute that dissolves in a given quantity of solvent at a specific temperature to produce a saturated solution, often expressed in $g/100\text{ mL}$.

Dynamic Equilibrium (in Solution)

The state reached when the rate of solute dissolution equals the rate of solution/crystallization, resulting in a constant amount of dissolved solute over time.

Saturated Solution

A solution in which the solvent holds the maximum possible amount of dissolved solute at a specified temperature, existing in dynamic equilibrium with undissolved solute.

Unsaturated Solution

A solution containing less solute than the maximum amount capable of dissolving in the solvent at that temperature.

Supersaturated Solution

An unstable solution holding more dissolved solute than is normally possible at a given temperature, from which excess solute crystallizes upon introducing a seed crystal or scratching the container.

Miscible

The property of two or more substances (liquids or gases) to dissolve completely in one another in all proportions to form a single phase.

Immiscible

The property of substances, typically liquids, that do not dissolve appreciably in each other and separate into distinct layers (such as hexane and water).

Henry's Law

A physical law stating that the solubility ($S_g$ or $c$) of a gas in a liquid is directly proportional to the partial pressure ($P_g$ or $P$) of that gas above the liquid ($S_g = k P_g$).

Thermal Pollution

The increase in water temperature in lakes and streams that lowers the solubility of dissolved oxygen ($O_2$), leading to oxygen depletion in deeper layers.

Molarity ($M$)

A concentration unit defined as the number of moles of solute dissolved per liter of solution ($\text{mol/L}$).

Molality ($m$)

A concentration unit defined as the number of moles of solute divided by the kilograms of solvent ($\text{mol/kg}$).

Mole Fraction ($X$ or $\chi$)

A dimensionless measure of concentration defined as the number of moles of a specific component divided by the total number of moles of all components in the mixture.

Colligative Properties

Physical properties of solutions that depend solely on the relative number of solute particles present in solution, regardless of their nature or chemical identity.

Vapor Pressure Lowering

The reduction in equilibrium vapor pressure of a solvent that occurs upon the addition of a nonvolatile solute.

Raoult's Law

The relationship stating that the vapor pressure of a solution ($P$) equals the product of the vapor pressure of the pure solvent (P^\tempcirc) and the mole fraction of the solvent ($X_1$), given by P = P^\tempcirc X_1.

Boiling Point Elevation ($\Delta T_b$)

The increase in the boiling point of a solvent caused by the addition of a nonvolatile solute, calculated via $\Delta T_b = K_b m$.

Molal Boiling-Point-Elevation Constant ($K_b$)

A solvent-specific constant representing the boiling point elevation produced by a $1.0\text{ m}$ solution of a nonvolatile nonelectrolyte solute, expressed in ^\tempcirc\text{C}/m.

Freezing Point Depression ($\Delta T_f$)

The decrease in the freezing point of a solvent caused by the addition of a solute, calculated via $\Delta T_f = K_f m$.

Molal Freezing-Point-Depression Constant ($K_f$)

A solvent-specific constant representing the freezing point depression produced by a $1.0\text{ m}$ solution of a solute, expressed in ^\tempcirc\text{C}/m.

Osmosis

The net movement of solvent molecules through a semipermeable membrane from an area of lower solute concentration (higher solvent concentration) toward an area of higher solute concentration.

Osmotic Pressure ($\Pi$)

The pressure required to completely prevent the net flow of solvent across a semipermeable membrane into a solution, calculated as $\Pi = MRT$.

Isotonic Solutions

Two or more solutions that possess the same osmotic pressure and identical effective solute particle concentrations across a semipermeable membrane.