Behaviour of Gases

• Gases contain particles that are free to move around, meaning they collide with the surface of any container and through colliding exert a force on that surface, the more frequent the collisions the greater the force.
• Pressure and volume (constant temperature)

  
• PRESSURE AND VOLUME (constant temperatur)

  • Pressure of the gas is inversely proportional to its volume - as volume increases, pressure decreases at decreasing rate.
• PRESSURE AND VOLUME (constant temperature)

  • Particles have less room to move around, so collide with surface of the container more frequently, applying more force (greater force = greater pressure).
• PRESSURE AND VOLUME (constant temperature)

  • p1 x V1 = p2 x V2
• Pressure and temperature (constant volume)

  
• PRESSURE AND TEMPERATURE (constant volume)

  • Pressure is directly proportional to the temperature in Kelvin - increasing temperature on fixed volume of gas, increases pressure at constant rate.
• PRESSURE AND TEMPERATURE (constant volume)

  • Particles move around more quickly and collide with surface of container more frequently - more force.
• PRESSURE AND TEMPERATURE (constant volume)

  • p1 / T1 = p2 / T2
• • Temperature (K) = Temperature (°C) + 273
• Volume and temperature (constant pressure)

  
• VOLUME AND TEMPERATURE (constant pressure)

  • Volume is directly proportional to the temperature - as temperature increases, volume increases (at constant rate) if pressure remains constant.
• VOLUME AND TEMPERATURE (constant pressure)

  • Particles (gain kinetic energy) move around more faster and collide with greater force on container walls more frequently forcing the particles further apart (pushing outwards, increasing volume).
• VOLUME AND TEMPERATURE (constant pressure)

  • V1 / T1 = V2 / T2
• Calculate unknown value:

  • p1 x V1 / T1 = p2 x V2 / T2
• ABSOLUTE ZERO

  • Graphs of Pressure against Temperature and Volume against Temperature don’t reach zero at 0°C - they reach zero at a temperature of -273°C, this temperature is known as absolute zero.
• • Absolute zero Kelvin temperature is where the gas molecules have zero kinetic energy and do not move around (no pressure, no collisions, no volume).
• • To determine the value of absolute zero in °C on a graph you can extend the line back (extrapolate) to 0 volume and read where the line crosses the axis.