Graham's law of diffusion

 

Graham's law of diffusion | chemistry class 11 | fsc part 1 | chemistry notes

Q) Define diffusion. Give examples.

Ans. The spontaneous mixing of the molecules of different gases by random motion and collisions to form a homogeneous mixture is called diffusion.

Examples:    i) The spreading of fragrance of rose in air

                   ii) The gases of balloon diffuse in air after its burst.

 

Q) Define effusion. Give examples.

Ans. The escaping of gas molecules one by one through a tiny hole into an evacuated space is called effusion.

Example: An inflated balloon gradually becomes smaller in size due to its effusion.

 

Q) State Graham’s law of diffusion. Write its mathematical form.

Ans. The rate of diffusion or effusion of a gas is inversely proportional to the square root of its density at constant temperature and pressure.

Mathematical form:

                             

 

Q) Lighter gases diffuse more rapidly than heavier gases. Give reason.

Ans. According to Graham’s law “Rate of diffusion of a gas is inversely proportional to square root of molar mass of the gas.

The equation is                =              

Hence, Lighter gases diffuse more rapidly than heavier gases.