Gases, Liquids, and Solids - CHEM 115

Comprehensive vocabulary flashcards covering the characteristic properties of matter, Kinetic Molecular Theory, gas laws, phase changes, and intermolecular forces based on the CHEM 115 lecture.

Compressibility

A measure of the change in volume of a sample of matter resulting from a change in pressure.

Thermal expansion

A measure of the change in volume of a sample of matter resulting from a change in temperature.

Kinetic Energy

Energy that matter possesses because particles are in motion; its amount depends on the temperature, where higher temperature equals higher kinetic energy.

Potential Energy

Stored energy that matter possesses as a result of its position, condition, and/or composition, dependent on electrostatic interactions between particles.

Electrostatic interaction

An attraction or repulsion that occurs between charged particles; particles of opposite charge attract, while particles of like charge repel.

Kinetic Molecular Theory

A set of five statements explaining the physical behavior of matter, assuming particles are in constant random motion unless at absolute zero.

Elastic collision

A collision in which total kinetic energy remains constant and no energy is lost, such as in a Newton’s cradle.

Inelastic collision

A collision in which the energy of motion is lost, such as two balls of putty colliding to form a "glob" with no resulting movement.

Pressure ($P$)

The force applied per unit area on an object resulting from gas particles colliding with the container wall.

Kelvin scale conversion

The formula used for gas laws where temperature in Kelvin ($K$) equals the temperature in degrees Celsius plus 273 ($K = {^{\circ}C} + 273$).

Boyle’s Law

States that the volume ($V$) of a fixed amount of gas is inversely proportional to the pressure ($P$) applied if the temperature ($T$) is kept constant ($P_1 \times V_1 = P_2 \times V_2$).

Charles’s Law

States that the volume ($V$) of a fixed amount of gas is directly proportional to its Kelvin temperature ($T$) if the pressure ($P$) is kept constant ($\frac{V_1}{T_1} = \frac{V_2}{T_2}$).

Combined Gas Law

States that the product of the pressure ($P$) and volume ($V$) of a fixed amount of gas is directly proportional to its Kelvin temperature ($T$) ($\frac{P_1 \times V_1}{T_1} = \frac{P_2 \times V_2}{T_2}$).

Ideal Gas Law

Describes the relationships among pressure ($P$), volume ($V$), molar amount ($n$), and temperature ($T$) using the equation $PV = nRT$.

Standard Temperature and Pressure (STP)

A set of standard conditions where temperature is $0\,^{\circ}C$ and pressure is $1\,atm$; one mole of gas at STP occupies $22.4\,L$.

Dalton’s Law of Partial Pressures

States that the total pressure ($P_{Total}$) exerted by a gas mixture is the sum of the partial pressures of the individual gases present ($P_{Total} = P_A + P_B + P_C + \dots$).

Partial pressure

The pressure that a specific gas in a mixture would exert if it were present alone under the same conditions.

Sublimation

An endothermic change of state where a substance transforms directly from a solid ($s$) to a gas ($g$).

Deposition

An exothermic change of state where a substance transforms directly from a gas ($g$) to a solid ($s$).

Physical equilibrium

A state in which two opposing physical processes, such as evaporation and condensation, take place at the same rate.

Vapor pressure

The pressure exerted by a vapor above a liquid when the liquid and vapor are in physical equilibrium with each other.

Volatile

A substance that readily changes from the liquid to the gas state at room temperature due to high vapor pressure.

Boiling point

The temperature at which the vapor pressure of a liquid equals the external or atmospheric pressure.

Normal boiling point

The temperature at which a liquid boils specifically at $760\,mm\,Hg$ or $1\,atm$.

Intermolecular forces

Electrostatic attractive forces that act between a molecule and another molecule, including dipole-dipole, hydrogen bonds, and London forces.

Dipole–dipole interaction

An intermolecular force occurring between polar molecules where the positive region of one molecule attracts the negative region of another.

Hydrogen bond

An extra-strong dipole-dipole interaction between a hydrogen atom bonded to a small, highly electronegative atom ($F$, $O$, or $N$) and a lone pair on another nearby $F$, $O$, or $N$.

London dispersion force

A weak, temporary intermolecular force caused by the formation of an instantaneous dipole; it is the only force present in nonpolar molecules.

Endothermic change of state

A process where heat energy is absorbed by the system, including evaporation, melting, and sublimation.

Exothermic change of state

A process where heat energy is given off by the system, including condensation, freezing, and deposition.