Introductory Chemistry - Chapter 10: Gases

Vocabulary practice flashcards covering Chapter 10: Gases from Corwin's Introductory Chemistry, including gas properties, pressure units, gas laws, the kinetic-molecular theory, and the ideal gas equation.

Properties of Gases

The five fundamental characteristics of gases: they have variable shape and volume, expand uniformly, compress uniformly, possess low density (air is about $0.001\,\text{g/mL}$ compared to $1.0\,\text{g/mL}$ for water), and mix uniformly with other gases in the same container to form homogeneous mixtures.

Gas Pressure

The force exerted per unit area as a result of constantly moving gas molecules striking the walls of their container. Increased temperature causes molecules to move faster and strike container walls more frequently and with greater force.

Atmospheric Pressure

The pressure produced by the air molecules in the environment. At sea level, standard atmospheric pressure supports a column of mercury measuring $29.9\,\text{in. Hg}$ ($760\,\text{torr}$).

Barometer

An instrument invented in 1643 by Evangelista Torricelli designed to measure atmospheric pressure by balancing environmental air pressure against a column of liquid mercury in an inverted glass tube.

Standard Pressure

The atmospheric pressure measured at sea level, defined as exactly $1\,\text{atm}$, $29.9\,\text{in. Hg}$, exactly $76\,\text{cm Hg}$, exactly $760\,\text{mm Hg}$, exactly $760\,\text{torr}$, $14.7\,\text{psi}$, or $101\,\text{kPa}$.

Torr

A unit of gas pressure defined as exactly equal to $1\,\text{mm Hg}$ of pressure, meaning standard pressure is exactly $760\,\text{torr}$.

Kilopascal (kPa)

The official SI unit of pressure, where standard pressure at sea level corresponds to $101\,\text{kPa}$.

Variables Affecting Gas Pressure

The three physical parameters that determine gas pressure: the volume of the container, the temperature of the gas, and the number of gas molecules present in the container.

Boyle's Law

The gas law stating that the volume of a gas is inversely proportional to its pressure at constant temperature ($V \propto \frac{1}{P}$), expressed mathematically as $P_1 V_1 = k = P_2 V_2$.

Charles's Law

The gas law discovered in 1783 by Jacques Charles stating that the volume of a gas is directly proportional to its Kelvin temperature at constant pressure ($V \propto T$), expressed mathematically as $\frac{V_1}{T_1} = k = \frac{V_2}{T_2}$.

Gay-Lussac's Law

The gas law discovered in 1802 by Joseph Gay-Lussac stating that the pressure of a gas is directly proportional to its Kelvin temperature at constant volume ($P \propto T$), expressed mathematically as $\frac{P_1}{T_1} = k = \frac{P_2}{T_2}$.

Combined Gas Law

A gas law combining Boyle's, Charles's, and Gay-Lussac's laws to express the simultaneous relationship between pressure, volume, and Kelvin temperature: $\frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2}$.

Vapor Pressure

The pressure exerted by the gaseous vapor above a liquid in a closed container when the rate of evaporation equals the rate of condensation; it increases with increasing temperature.

Dalton's Law of Partial Pressures

The law stating that the total pressure exerted by a mixture of gases is equal to the sum of the individual partial pressures exerted by each gas: $P_{\text{total}} = P_1 + P_2 + P_3 + \dots$.

Partial Pressure

The individual pressure exerted by a specific gas present within a gaseous mixture.

"Wet" Gas

A gas collected in the laboratory by water displacement, which contains both the target gas and evaporated water vapor ($P_{\text{atm}} = P_{\text{gas}} + P_{\text{H}_2\text{O}}$).

Kinetic–Molecular Theory of Gases

A theoretical model describing gas behavior based on five core postulates: gases consist of tiny molecules; gas molecules travel rapidly in straight lines in random directions; molecules exhibit no attraction for one another; collisions are completely elastic (no energy lost); and the average kinetic energy of the molecules is directly proportional to the Kelvin temperature ($\text{KE} \propto T$).

Absolute Zero

The theoretical minimum temperature where the pressure and volume of a gas extrapolate to zero, corresponding to $0\,\text{Kelvin}$ ($-273\,^\circ\text{C}$).

Ideal Gas Law

The equation of state for an ideal gas that combines pressure, volume, amount in moles, and temperature: $PV = nRT$.

Ideal Gas Constant (R)

The universal proportionality constant in the ideal gas equation, having a numerical value of $0.0821\,\frac{\text{L}\cdot\text{atm}}{\text{mol}\cdot\text{K}}$.

Standard Temperature and Pressure (STP)

The standard reference conditions used in gas calculations, defined as exactly $1\,\text{atmosphere}$ ($1.00\,\text{atm}$) of pressure and a temperature of $0\,^\circ\text{C}$ ($273\,\text{K}$).