Pressure’s Law

Pressure Law

Pressure law states that for a fixed mass of gas, the pressure of the gas is directly proportional to the absolute temperature of the gas provided the volume of the gas is kept constant.



  1. The kinetic energy of gas molecules increases with temperature.
  2. The air molecules collide with the wall of the container at higher velocity and frequency.
  3. The pressure in the gas increases, causing an increase in volume.


  1. In the graphs above, the first graph shows that P is directly proportional to the absolute temperature.
  2. The second graph shows that, if the temperature is in °C, the graph does not pass through the origin.
  3. The third and the forth graphs shows that P/T is always constant for all value of P and T.