Physics Form 4: Chapter 4 - Boyle's Law of Gas

Boyle's law states that the pressure of a fixed mass of gas is inversely proportional to the volume of gas provided the temperature of the gas is constant.

The law was first proposed in 1662 by Robert Boyle

Because pV = constant that means that p₁V₁ = constant and so does p₂V₂. We can therefore write:

 

where

V₁ = equals the original volume,

V₂  = equals the new volume,

p₁  = the original pressure, and

p₂  = the new pressure.

Explanation of Boyle's law by the kinetic theory:

 

• At constant temperature, the average kinetic energy of the gas molecules is constant.
• When the gas is compressed, the volume is decreased. Therefore, the number of molecules per unit volume will increase.
• The rate of collision of the gas molecules with the wall of container will increase.
• Thus, the pressure of gas increases.