Properties and Gas Laws Quiz

Properties of Gases

• Gases expand indefinitely to fill their container.
• Gases have no definite shape, taking the shape of their container.
• Gases are highly compressible due to the large spaces between gas molecules.
• Gases mix evenly and completely when combined in the same container.
• Gases have much lower densities than liquids and solids.

The Gas Laws

• Ideal Gas Law: PV = nRT, where P = pressure, V = volume, n = moles, R = ideal gas constant (0.0821 L atm K^-1 mol^-1), and T = absolute temperature.
• Boyle's Law: At constant temperature, the volume of a gas is inversely proportional to its pressure. (P₁V₁ = P₂V₂)
• Charles's Law: At constant pressure, the volume of a gas is directly proportional to its absolute temperature. (V₁/T₁ = V₂/T₂)
• Avogadro's Law: Equal volumes of different gases at the same temperature and pressure contain the same number of molecules (or moles). (V = nk₃)
  • The molar volume of an ideal gas at STP (Standard Temperature and Pressure: 0°C and 1 atm) is 22.4 L.
• Combined Gas Law: P₁V₁/T₁ = P₂V₂/T₂, relates changes in pressure, volume, and temperature for a fixed amount of gas.

Gas Density

• Gas density (d) is calculated as d = m/V, where m is the mass and V is the volume.
• The density of a gas is directly proportional to its molar mass.
• Gas density increases with increasing pressure and decreases with increasing temperature.

Dalton's Law of Partial Pressures

• The total pressure of a gas mixture is the sum of the partial pressures of each component gas. (P_t = P_A + P_B + P_C + ...)
• The partial pressure of a gas is proportional to its mole fraction in the mixture. (P_A = X_AP_t)
• When gases are collected over water, the total pressure is the sum of the partial pressure of the collected gas and the partial pressure of water vapor. (P_t = P_gas + P_H2O)