Liquids, Solids, and Intermolecular Forces Flashcards

Vocabulary flashcards generated from lecture notes on liquids, solids, intermolecular forces, surface tension, viscosity, vaporization, and phase diagrams.

Crystalline Solid

A solid in which atoms or molecules are arranged in geometric patterns with long-range, repeating order (e.g., salt, diamond).

Amorphous Solid

A solid in which atoms or molecules do not have long-range, repeating order (e.g., glass, rubber, plastic).

Dispersion Force

A weak intermolecular attractive force caused by temporary polarity in molecules due to unequal electron distribution; also called the London force.

Dipole-Dipole Force

An intermolecular attraction resulting from the positive end of a polar molecule attracting the negative end of a neighboring polar molecule.

Hydrogen Bonding

An unusually strong dipole-dipole attraction occurring only in compounds where hydrogen is covalently bonded directly to highly electronegative elements ($N$, $O$, or $F$).

Ion-Dipole Force

The attraction between an ion from an ionic compound and the permanent dipole of a polar molecule in a mixture, representing the strongest type of intermolecular force.

Polarizability

The ease with which an electron cloud can be distorted to form an instantaneous dipole, which increases with larger electron cloud volume and higher molar mass.

Volatile Liquid

A liquid that evaporates easily at normal temperatures due to weak intermolecular attractive forces (e.g., gasoline, fingernail polish remover).

Nonvolatile Liquid

A liquid that does not evaporate easily at normal temperatures due to stronger intermolecular forces (e.g., motor oil).

Surface Tension

The energy required to increase the surface area of a liquid by a given amount, caused by molecules at the surface experiencing fewer attractive forces than bulk interior molecules.

Viscosity

A measure of a liquid's resistance to flow, typically measured in poise ($1\text{ P} = 1\text{ g}/(\text{cm}\times\text{s})$) or centipoise ($\text{cP}$).

Capillary Action

The ability of a liquid to flow up a narrow tube against the influence of gravity through the combined effects of cohesive and adhesive forces.

Cohesive Forces

Intermolecular attractive forces between identical liquid molecules within a fluid.

Adhesive Forces

Intermolecular attractive forces between liquid molecules and the surface of a solid container or tube.

Concave Meniscus

A curved, U-shaped upper liquid surface formed in a glass tube when adhesive forces between the liquid and the wall are stronger than cohesive forces within the liquid.

Convex Meniscus

A curved, upward-domed liquid surface formed in a glass tube when cohesive forces within the liquid are stronger than adhesive forces between the liquid and the wall.

Vaporization

An endothermic process in which surface liquid molecules gain sufficient thermal kinetic energy to overcome intermolecular forces and escape into the gas phase.

Condensation

An exothermic phase change process in which vapor molecules lose thermal energy through collisions and transition into the liquid phase.

Heat of Vaporization ($ΔH_{\text{vap}}$)

The enthalpy change representing the amount of heat energy required to vaporize $1\text{ mol}$ of a liquid at a given temperature.

Dynamic Equilibrium

The state reached in a closed system when the rate of evaporation of a liquid equals the rate of condensation of its vapor.

Vapor Pressure

The pressure exerted by a vapor that is in dynamic equilibrium with its liquid phase in a closed container.

Boiling Point

The temperature at which a liquid's vapor pressure equals the surrounding external atmospheric pressure.

Normal Boiling Point

The specific temperature at which the vapor pressure of a liquid equals $1\text{ atm}$ ($760\text{ torr}$).

Clausius-Clapeyron Equation

An equation relating vapor pressure ($P_{\text{vap}}$) and absolute temperature ($T$) linearly in logarithmic form: $\ln P_{\text{vap}} = -\frac{\Delta H_{\text{vap}}}{RT} + \ln \beta$.

Sublimation

An endothermic phase transition in which a substance converts directly from a solid to a gas without passing through the liquid state.

Fusion

An endothermic phase change process in which a solid absorbs heat and melts into a liquid state.

Heat of Fusion ($ΔH_{\text{fus}}$)

The enthalpy change representing the amount of heat energy required to melt $1\text{ mol}$ of a solid substance.

Phase Diagram

A graph illustrating the physical state of a substance as a function of temperature and pressure, where bounded regions represent states and lines represent phase boundaries.

Triple Point

The unique temperature and pressure condition on a phase diagram at which the solid, liquid, and gas phases of a substance coexist in dynamic equilibrium.

Critical Point

The temperature and pressure condition terminating the vapor pressure curve beyond which a distinct liquid phase cannot exist.