Intermolecular Forces, Solutions, and Chemical Kinetics Flashcards

This set of flashcards covers key vocabulary and concepts from Chapters 12, 13, 16, and 24, including intermolecular forces, solution properties, concentration units, colligative properties, and chemical kinetics.

Intramolecular forces

Bonding forces that exist within each molecule, such as ionic, covalent, or metallic bonding, which determine chemical behavior.

Intermolecular forces

Nonbonding forces between molecules that arise from attractions between molecules with partial charges or between ions and molecules; they determine physical properties.

Van der Waals distance

The closest distance where intermolecular attractions balance electron cloud repulsions.

Ion-Dipole Force

The intermolecular attractive force between an ion and a polar molecule (dipole), typically found in mixtures.

Dipole-Dipole Force

The intermolecular attraction between oppositely charged poles of nearby polar molecules; exists only for polar molecules.

Hydrogen bond

A specific type of dipole-dipole force that forms when the partially positive $H$ of one molecule is attracted to the partially negative lone pair on the $N$, $O$, or $F$ of another molecule.

Dispersion (London) Forces

The intermolecular attraction between all particles as a result of instantaneous polarizations of their electron clouds; primarily responsible for the condensed states of nonpolar substances.

Surface Tension

A measure of the energy required to increase a liquid's surface area, resulting from a net downward force on surface molecules.

Capillarity

The rising of a liquid through a narrow space occurring when adhesive forces (between liquid and surface) are greater than cohesive forces (within the liquid).

Viscosity

The resistance of a fluid to flow, which depends on molecular shape and decreases as temperature increases.

Solubility ($S$)

The maximum amount of solute that dissolves in a fixed quantity of a given solvent at a given temperature when an excess of solute is present.

Miscible

A term describing liquids that are soluble in each other in any proportion.

Hydration shells

Clusters of water molecules that surround an ion as it separates from a crystal structure during dissolution.

Ion-induced dipole forces

Forces that occur when the charge of an ion causes a distortion in the electron cloud of a nonpolar particle.

Polarizability

The ease with which a particle's electron cloud can be distorted; smaller particles are generally less polarizable than larger ones.

Soap

A salt formed from a strong base and a fatty acid, consisting of a nonpolar hydrocarbon tail and a polar-ionic head (typically a $-COO^-$ group).

Alloy

A mixture of elements that has metallic character; can be substitutional (atoms replaced) or interstitial (spaces filled).

Heat of solution ($\Delta H_{soln}$)

The total enthalpy change that occurs when solute and solvent form a solution, defined as $\Delta H_{soln} = \Delta H_{solute} + \Delta H_{solvent} + \Delta H_{mix}$.

Charge density

The ratio of an ion's charge to its volume; higher charge density leads to more negative $\Delta H_{hydr}$ values.

Entropy ($S$)

A thermodynamic variable directly related to the number of ways a system can distribute its energy; solutions usually have higher entropy than pure components.

Saturated solution

A solution at equilibrium that contains the maximum amount of dissolved solute at a given temperature in the presence of undissolved solute.

Henry's Law

A law stating that the solubility of a gas ($S_{gas}$) is directly proportional to the partial pressure of the gas ($P_{gas}$) above the solution: $S_{gas} = k_H \times P_{gas}$.

Molarity ($M$)

A concentration unit defined as the amount (mol) of solute divided by the volume (L) of solution: $M = \frac{\text{mol solute}}{\text{L solution}}$.

Molality ($m$)

A concentration unit independent of temperature, defined as the amount (mol) of solute divided by the mass (kg) of solvent: $m = \frac{\text{mol solute}}{\text{kg solvent}}$.

Mole fraction ($X$)

The ratio of the amount (mol) of a solute to the total amount (mol) of all components in the solution.

Colligative property

A property of a solution that depends on the number, rather than the identity, of solute particles.

Raoult's Law

States that the vapor pressure of the solvent above a solution ($P_{solvent}$) equals the mole fraction of the solvent ($X_{solvent}$) times the vapor pressure of the pure solvent ($P^0_{solvent}$).

Boiling point elevation ($\Delta T_b$)

The phenomenon where the boiling point of a solution is higher than that of the pure solvent because of vapor pressure lowering.

Osmotic Pressure ($\Pi$)

The pressure that must be applied to a solution to prevent the net movement of solvent from the pure solvent side through a semipermeable membrane.

Chemical kinetics

The study of reaction rates, focusing on how fast the change from reactants to products occurs.

Reaction rate

The change in concentrations of reactants or products as a function of time: $\text{Rate} = -\frac{\Delta(\text{conc A})}{\Delta t}$.

Instantaneous rate

The reaction rate at a particular instant during the reaction, determined by the slope of a line tangent to the concentration-time curve.

Initial rate

The instantaneous rate at the moment the reactants are mixed ($t = 0$), which is the fastest rate during the reaction.

Rate Law

An equation that expresses the reaction rate as a function of reactant concentrations and temperature: $\text{Rate} = k[A]^m[B]^n$.

Rate constant ($k$)

The proportionality constant in the rate law that is specific to a reaction at a given temperature and does not change as the reaction proceeds.

Reaction order

The exponent in the rate law that shows how the rate is affected by changes in the concentration of a specific reactant.

Half-life ($t_{1/2}$)

The time required for the reactant concentration to reach half of its initial value.

Activity ($A$)

The decay rate of a radioactive sample, defined as the change in the number of nuclei ($N$) divided by the change in time ($t$).

Becquerel (Bq)

The SI unit of radioactivity, equivalent to one disintegration per second ($1\,\text{d/s}$).

Curie (Ci)

A common unit of radioactivity equivalent to $3.70 \times 10^{10}\,\text{d/s}$.