Gases Rapid Review for AP Chemistry

By — McGraw-Hill Professional
Updated on Feb 9, 2011

For a more thorough review, refer to these concepts:

Rapid Review

  • Kinetic Molecular Theory—Gases are small particles of negligible volume moving in a random straight-line motion, colliding with the container walls (that is the gas pressure) and with each other. During these collisions no energy is lost, but energy may be transferred from one particle to another; the Kelvin temperature is proportional to the average kinetic energy. There is assumed to be no attraction between the particles.
  • Pressure—Know how a barometer operates and the different units used in atmospheric pressure.
  • Boyle's law—The volume and pressure of a gas are inversely proportional if the temperature and amount are constant.
  • Charles's law—The volume and temperature of a gas are directly proportional if the amount and pressure are constant.
  • Gay-Lussac's law—The pressure and temperature of a gas are directly proportional if the amount and volume are constant.
  • Combined gas law—Know how to use the combined gas equation P1V1/T1 = P2V2/T1.
  • Avogadro's law—The number of moles and volume of a gas are directly proportional if the pressure and temperature are constant. Remember that 1 mol of an ideal gas at STP(1 atm & 0°C) occupies a volume of 22.4 L.
  • Ideal gas equation—Know how to use the ideal gas equation PV = nRT.
  • Dalton's law—The sum of the partial pressures of the individual gases in a gas mixture is equal to the total pressure: PTotal = PA + PB + Pc + …
  • Graham's law—The lower the molecular mass of a gas, the faster it will effuse/diffuse. Know how to use Graham's law: .
  • Gas stoichiometry—Know how to apply the gas laws to reaction stoichiometry problems.
  • Non-ideal gases—Know how the van der Waals equation accounts for the non-ideal behavior of real gases.
  • Tips—Make sure the temperature is in kelvin; gas laws are being applied to gases only; the units cancel; and the answer is reasonable.
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