The Gas Phase (College Board AP® Chemistry)

The Gas Phase

• Gases have several characteristics that differentiate them from solids and liquids;

  • Unlike solids and liquids, the particles of gases have very little intermolecular force and are in constant linear random motion

  • Given the little intermolecular force and constant random motion of the particles, gases neither have fixed volume nor shape

  • Gases are also highly compressible as a result of the large distance between particles and

  • Gases have much lower densities than liquids or solids

• Also for gases, unlike for liquids and solids, the relationship between pressure, volume, temperature, and molar amount of substance can be established with fair accuracy by one simple equation, the ideal gas law

  • The pressure of a gas is a measure of the collisions of its particles with the walls of its container

    • The magnitude of the pressure is determined by how often (frequency) and how forcefully the molecules strike the walls

  • Temperature of gas is an indicator of the average kinetic energy possessed by the particles of the gas

    • Hence, an increase in temperature is an increase in average kinetic energy and an increase in the molecular motion of the particles

  • The molecular interpretations of the temperature and pressure of a gas are explained by the kinetic molecular theory

Gas Particles

Diagram showing the arrangement and movement of gas particles