Particle model & pressure

• Gases:


  consist of a large number of small particles, which are molecules or atoms.

  • These particles are in CONSTANT RANDOM MOTION & move in straight lines, until they collide with either the container walls / other particles.

  
• As the TEMPERATURE of a gas rises, the SPEED of its molecules increases.

  • As the temperature is a measure of the AVERAGE KINETIC energy of the molecules in a substance.
• When VOLUME of the gas is constant & increase the temperature, the kinetic energy will increase meaning the molecules move faster.
• PRESSURE in a gas is the result of COLLISIONS between the gas molecules & the container walls.

  The UNITS for pressure can be measured in:

  • Pascals (Pa) or Atmospheres (atm.)

  
• The MORE MOLECULES in a given volume, the HIGHER the pressure.

  • As gas molecules collide MORE FREQUENTLY & with GREATER FORCE against the container walls.

  
• If we heat a gas up, the molecules:

  • gain KINETIC ENERGY
  • move at HIGHER SPEEDS
  • leading to MORE FREQUENT & FORCEFUL collisions with the container walls.
  • which INCREASES the PRESSURE.

  
• At a CONSTANT VOLUME, an INCREASE in TEMPERATURE will lead to an INCREASE in PRESSURE.