Diffusion

Diffusion

The spreading and mixing of particles of matter from one substance to another is called diffusion. This diffusion takes place due to the motion of particles from one substance to another.

1.Diffusion is fast in gases whereas in solids it is very slow: diffusion is faster in gases as the particles of gases move more freely, the force of attraction between the molecules are less so they can move independently. In case of liquids the movement of molecules is restricted so they move little slower than gases. In case of solid the intermolecular force is very strong so they rarely move, thus making diffusion very slow in case of solids.

2.Rate of diffusion increases with increase in temperature: when a substance is heated the particles of that substance get kinetic energy so they start moving rapidly making diffusion faster.

Diffusion explained with example:

Diffusion in gases:

1.      Smell of food cooked in kitchen reach us in other room: when food is cooked the gases released from the food contain smell with it. These gas particles containing aroma mix up with the surrounding air and rapidly move ahead to reach us.

2.      Smell of perfume spread due to diffusion.

3.      Smell of warm food can be observed from a distance but to smell the same food when cold we have to get close to it.

Diffusion in liquids:

1.      Crystal of potassium permanganate when placed in water and left undisturbed mixes with each other is due to diffusion. The particles of potassium permanganate spread in water due to diffusion.

2.      A drop of ink spreads in water as the small particles of ink move inside water due to diffusion.

Diffusion in solids:

1.      Two metal blocks when left together close to each other the particles of both diffuse with each other

2.      When blackboard scribbled with chalk is left that way for some time, we cannot clean the board quickly this happens because the particles of chalk diffuse in board and so it gets difficult to remove chalk particles from the board.