Graham’s Law of Effusion

multiplied by the mass of the molecule multiplied by the square of its velocity. The thermal energy of a system is the total kinetic energy of all particles of a system. As you can see by the equation, the kinetic energy is closely related to its velocity. Kinetic energy theory helps to lay down the three major laws of gases as already described.

GRAHAM’S LAW OF EFFUSION

The process of effusion involves the escape of gas molecules through a small hole into a vacuum. The assumption is that, during the exit, there are no collisions on the molecule that is exiting. According to this law, the lighter molecules will exit first because they are moving faster. The relationship has been described in the law stating that the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles.

Diffusion is more complicated than effusion because there are intermolecular forces involved in diffusion that are not presumed to be a factor in effusion. The molecules that diffuse across an area will collide with existing molecules in the space and will not exit into a vacuum that is the case with effusion. The truth is that, along with effusion, molecules will differ in their rate of diffusion in that larger molecules will diffuse at a decreased rate compared to lighter and less dense molecules.