General, Organic, and Biological Chemistry: Chapter 8 Gases

Flashcards covering the properties of gases, gas laws (Boyle's, Charles's, Gay-Lussac's, Avogadro's, Combined, Ideal, and Dalton's), STP conditions, and biological gas exchange applications.

Kinetic Molecular Theory

A model describing a gas as small particles in constant, random motion in straight lines, where the Kelvin temperature is proportionate to the average kinetic energy of the molecules.

Pressure ($P$)

The force exerted by a gas against the walls of its container, measured in units like atmosphere ($\text{atm}$), millimeter of mercury ($\text{mmHg}$), torr ($\text{Torr}$), or pascal ($\text{Pa}$).

Volume ($V$)

The space occupied by a gas, typically measured in liters ($L$) or milliliters ($mL$), which is equal to the volume of the container.

Temperature ($T$)

The factor that determines the kinetic energy of gas particles; it must be converted to kelvins ($K$) for all gas law calculations.

Amount ($n$)

The quantity of gas present in a container, measured in grams ($g$) or moles ($n$); moles are required for gas law calculations.

Atmospheric Pressure

The pressure exerted by a column of air extending from the top of the atmosphere to the surface of Earth, identifying as approximately $1\,\text{atm}$ at sea level.

Unit Equivalents for 1 atm

$1\,\text{atm}$ is exactly equal to $760\,\text{mmHg}$, $760\,\text{Torr}$, $29.9\,\text{inHg}$, $14.7\,\text{psi}$, $101\,325\,\text{Pa}$, or $101.325\,\text{kPa}$.

Boyle’s Law

The inverse relationship between the pressure and volume of a gas, stated as $P_1V_1 = P_2V_2$ when temperature ($T$) and amount ($n$) remain constant.

Inhalation

The process where the lungs expand and the pressure in the lungs decreases, causing air to flow toward the lower pressure in the lungs.

Exhalation

The process where lung volume decreases and pressure within the lungs increases, causing air to flow from the lungs to the outside.

Charles’s Law

The direct relationship between the Kelvin temperature and the volume of a gas, expressed as $\frac{V_1}{T_1} = \frac{V_2}{T_2}$ when pressure ($P$) and amount ($n$) are constant.

Gay-Lussac’s Law

The direct relationship between the pressure and Kelvin temperature of a gas, expressed as $\frac{P_1}{T_1} = \frac{P_2}{T_2}$ when volume ($V$) and amount ($n$) are constant.

Vapor Pressure

The pressure created by vapor accumulating at the surface of a liquid in a closed container.

Boiling Point

The temperature at which the vapor pressure of a liquid becomes equal to the external (atmospheric) pressure.

Combined Gas Law

A gas law that combines Boyle's, Charles's, and Gay-Lussac's laws into the expression $\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$ for a constant amount of gas ($n$).

Avogadro’s Law

The law used to calculate the relationship between the volume and the amount (moles) of a gas when pressure ($P$) and temperature ($T$) do not change.

Standard Temperature and Pressure (STP)

Conditions set at a temperature of $273\,\text{K}$ ($0^\circ\text{C}$) and a pressure of $1\,\text{atm}$ ($760\,\text{mmHg}$).

Molar Volume at STP

The volume occupied by $1\,\text{mole}$ of any gas at STP, which is approximately $22.4\,L$.

Ideal Gas Law

The single expression combining four gas properties ($P$, $V$, $n$, and $T$), written as $PV = nRT$.

Ideal Gas Constant ($R$)

A constant used in the ideal gas law, valued at $0.0821\,L\cdot\text{atm}/(\text{mole}\cdot K)$ or $62.4\,\text{mmHg}\cdot L/(\text{mole}\cdot K)$.

Partial Pressure

The pressure that each individual gas in a mixture would exert if it were alone in the container.

Dalton’s Law of Partial Pressures

A law stating that the total pressure of a gas mixture is the sum of the partial pressures of those gases ($P_{\text{total}} = P_1 + P_2 + P_3 + \dots$).

Oxygen Exchange in Blood

$O_2$ flows into the tissues from the blood because the partial pressure of $O_2$ is higher in the blood ($100\,\text{mmHg}$) and lower in the tissues ($30\,\text{mmHg or less}$).

Carbon Dioxide Exchange in Blood

$CO_2$ flows out of the tissues into the blood because the partial pressure of $CO_2$ is higher in the tissues ($50\,\text{mmHg or greater}$) and lower in the blood ($40\,\text{mmHg}$ in oxygenated blood).