GASES

• the variables affecting the behavior of gases are:

  1. volume
  2. pressure
  3. temperature
• volume is the space occupied by matter in three-dimensional units
• volume is usually expressed in liters (L) or cubic centimeter (cc or ccm^3)
• pressure is the force per unit area exerted by the gas on its container
• pressure is usually measured by a barometer in Hg or atmosphere
• Hg (1 mm Hg = 1 Torr)
• atomsphere (1 atm = 760 mm Hg)
• temperature is usually expressed in kelvin
• STP (standard temperature and pressure)
• standard temperature: 0 degrees celsius or 273 kelvin
• standard pressure: 1 atm or 760 mmHg or 101.3 kPa
• the gas laws are:

  1. boyle's law
  2. charles' law
  3. avogadro's law
  4. ideal gas law
  5. dalton's law of partial pressure
  6. graham's law of effusion
  7. gay-lusaac's law
  8. combined gas law
• Boyle's Law states that the volume of a fixed mass of gas at constant temperature varies inversely with its absolute pressure.
• Charles' Law states that the volume of a given mass of gas at constant pressure is directly proportional to its Kelvin temperature.
• Avogadro's Law states that equal volumes of all gases, under the same conditions of temperature and pressure, contain an equal number of molecules.
• Ideal Gas Law states that the product of the pressure and volume of a given amount of gas is directly proportional to the absolute temperature of the gas.
• Dalton's Law of Partial Pressure states that when two or more gases occupy the same container, the total pressure exerted by them is equal to the sum of their individual pressures.
• The Ideal Gas Law states that PV = nRT where P is pressure (in pascals), V is volume (in cubic meters), n is amount of substance (in moles), R is ideal gas constant (8.31 J/mol K) and T is temperature (in Kelvins).
• Graham's Law of Effusion states that the rate of escape of a gas through a small hole is inversely proportional to the square root of its density.
• Combined Gas Law states that the product of the pressure, volume, and absolute temperature of a gas is always constant as long as there is no change in the quantity of gas present.
• Gay-Lussac's Law states that if the volume of a gas increases, then the pressure decreases proportionally.
• kinetic molecular theory of gases : for ideal gases
• under KMTG, the movement of particles is in continuous random motion
• the pressure of the gas is due to the bombardment of molecules in the container
• collisions between or among particles are elastic
• the kinetic energy of a system is proportional to temperature
• the wide separation of molecules cause the attractive and repulsive forces to be negligible