Ideal Gas Molecules

Ideal Gas Molecules

Characteristics of Ideal Gas Molecules

  • Ideal gas molecules are assumed to be point mass particles, meaning they have mass but no volume.
  • These molecules are in constant, random motion, colliding with each other and the walls of their container.
  • The collisions are considered perfectly elastic. This means the total kinetic energy of the molecules before and after the collision remains the same.
  • These molecules have no intermolecular forces between them. They do not attract or repel each other.
  • The individual gas molecules themselves are neutral, they have no charge.

Behaviour of Ideal Gas Molecules

  • The average kinetic energy of ideal gas molecules is directly proportional to temperature. Increase in temperature results in higher average kinetic energy of the molecules.
  • Ideal gas molecules spread out to fill their entire container, regardless of its shape or size. This is due to their constant random motion.
  • The pressure exerted by an ideal gas is due to the collisions of its molecules with the walls of the container. The more frequent the collisions, the higher the pressure.
  • According to the kinetic theory of gases, the speed of gas particles increases as the temperature increases, leading to more collisions and a higher pressure.
  • The behaviour of real gases can be predicted fairly accurately at normal temperatures and pressures using the ideal gas laws, but these laws become less accurate under extreme conditions.

Ideal Gas Laws

  • The Ideal Gas Law is written as PV = nRT where P is the pressure, V is the volume, n is the number of moles of the gas, R is the gas constant, and T is temperature.
  • The law states that the volume of a given amount of gas is directly proportional to its temperature on the absolute temperature scale (Kelvin), if the pressure is kept constant (Charles’s Law).
  • It also affirms that the pressure of a given amount of gas is directly proportional to its absolute temperature, if the volume is kept constant (Gay-Lussac’s Law).
  • Lastly, pressure is inversely proportional to volume for a fixed amount of gas at a constant temperature (Boyle’s Law).