Gas Chemistry

Gas Chemistry Introduction

  • Gas chemistry focuses on understanding the physical and chemical properties of gases.
  • The kinetic theory of gases assumes that gas particles are in constant random motion and that they constantly collide with each other and the walls of their container.
  • Pressure of a gas arises from the collisions of the gas molecules with the walls of their container.

Gas Laws

  • The boyle’s law states the pressure of a gas is inversely proportional to its volume, if the temperature and quantity of gas remain unchanged.
  • The charles’s law states the volume of a gas is directly proportional to its absolute temperature (Kelvin), if the pressure and quantity of gas remain unchanged.
  • The avogadro’s law explains equal volumes of gases, at the same temperature and pressure, contain the same number of molecules.

Ideal Gases

  • An ideal gas is a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory.
  • The universal gas equation or the ideal gas law is given as PV=nRT, where P is pressure, V is volume, n is number of moles, R is gas constant and T is temperature.
  • Ideal gases are assumed to exist under ideal conditions which are not always possible practically.

Real Gases

  • Real gases deviate from the behaviour of ideal gases due to the finite size of their molecules and attractions between them.
  • The van der Waals equation accounts for these deviations by introducing correction factors in the pressure and volume terms of the ideal gas equation.

Gas Mixtures and Partial Pressure

  • In a mixture of gases, the total pressure exerted is the sum of the pressures that each gas would exert if it were alone (Dalton’s Law of Partial Pressures).
  • The individual pressure of each gas in a mixture is its partial pressure and it depends on its mole fraction in the mixture.

Real-world Applications of Gas Chemistry

  • Understanding gas chemistry has practical implications in areas such as tyre pressure monitoring, scuba diving calculations, aerosol propellants, and hot air balloons.
  • Knowledge on real gases, ideal gases, partial pressures, and gas laws assist in studying climate change, atmospheric pressure changes and pollutant dispersal in the environment.