Question

Define diffusion. State the factors on which diffusion depends.

Answer 1

The spontaneous intermixing of particles of matter on their own is called diffusion.

Diffusion is a property of matter which is based on the motion of its particles. Diffusion occurs in gases, liquids, and solids.

Factors affecting the rate of diffusion

1. Density - The rate of diffusion is inversely proportional to the square root of density according to Graham's Law. r $\mathrm{\alpha }$ 1/ $\sqrt{d}$. Therefore, lighter gases (such as $\mathrm{Hydrogen}\left({\mathrm{H}}_2\right),\mathrm{Methane}\left({\mathrm{CH}}_4\right),\mathrm{Ammonia}\left({\mathrm{NH}}_3\right)$, etc.) diffuse faster than heavy gases (such as HCl, $\mathrm{Oxygen}\left({\mathrm{O}}_2\right),\mathrm{Nitrogen}\left({\mathrm{N}}_2\right),\mathrm{Carbon}\mathrm{dioxide}\left({\mathrm{CO}}_2\right)\mathrm{etc}$).
   
2. Temperature - The rate of diffusion increases with the rise in temperature. This is because when the temperature of a substance is increased by heating, its particles gain kinetic energy and move more rapidly. This increase in the speed of the particles of a substance increases the rate of diffusion.
   
3. Pressure - Rate of diffusion also increases in pressure, e.g. a punctured tire at a higher pressure becomes flat than the punctured tire at low pressure.