Chapter 10: Gases

Flashcards about the properties of gases

What are the four parameters that completely describe the physical state of a gas?

Temperature (T), Pressure (P), Volume (V), and number of moles (n)

List four characteristics of gases.

1. Gases assume the shape and volume of their container. 2. Gases are compressible. 3. Gases have densities much smaller than those of liquids and solids and are highly variable. 4. Gases form homogeneous mixtures in any proportion.

Define pressure and its SI unit.

Pressure is the force applied per unit area. The SI unit of force is the newton (N), and the SI unit of pressure is the pascal (Pa), defined as 1 newton per square meter.

What is standard atmospheric pressure in kPa, mmHg, and atm?

Approximately 101 kPa, 760 mmHg, or 1 atm

What is Boyle's Law?

For a fixed amount of gas at constant temperature, pressure and volume are inversely proportional (P₁V₁ = P₂V₂).

What is Charles's and Gay-Lussac's Law?

For a fixed amount of gas at constant pressure, volume and temperature are directly proportional (V₁/T₁ = V₂/T₂), where temperatures are in Kelvin.

What is Avogadro's Law?

At constant temperature and pressure, volume is directly proportional to the number of moles (V ∝ n).

State the combined gas law.

For a fixed amount of gas, (P₁V₁)/T₁ = (P₂V₂)/T₂.

What are the conditions for Standard Temperature and Pressure (STP)?

Exactly 0°C and 1 atm pressure.

What is the molar volume of any gas at STP?

22.4 L/mol

State the ideal gas equation.

PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature in Kelvin.

List two applications of the ideal gas equation

Calculating the required volume of a gaseous reactant and predicting the volume of a gaseous product

What is Dalton's Law of Partial Pressures?

The total pressure exerted by a gas mixture is the sum of the partial pressures exerted by each component of the mixture: Ptotal = P₁ + P₂ + P₃ + …

Define mole fraction.

The ratio of the number of moles of a component in a mixture to the total number of moles of all components in the mixture.

State the four basic assumptions (postulates) of the kinetic molecular theory

1. Gases are composed of particles separated by large distances, and the volume of individual molecules is negligible.
2. Gas molecules are in constant random motion, colliding with the walls and each other in perfectly elastic collisions.
3. Gas molecules do not exert attractive or repulsive forces on one another.
4. The average kinetic energy of gas molecules is proportional to the absolute temperature.

What is diffusion?

The mixing of gases as a result of random motion and frequent collisions.

What is effusion?

The escape of gas molecules from a container to a region of vacuum.

What is Graham's Law?

The rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass.

Describe two factors that cause deviation from ideal behavior.

1. At high pressures, gas molecules are relatively close together, making the volume occupied by individual molecules more significant.
2. At low temperatures, gas molecules are moving more slowly, and the magnitude of intermolecular forces becomes more significant.