1.2 Diffusion

 Diffusion is the movement of particles from a region of high concentration to a region of low concentration, down the concentration gradient, as a result of their random movement.

Diffusion only occurs in fluids: gases and liquids 

It occurs fastest in gases as compared to in liquids because the gaseous particles have more energy; thus, they move quickly than the liquid particles.

The factors that affect the rate of diffusion:

•  temperature

• the relative molecular masses.

Diffusion in liquids

An example:

When Potassium (IV) manganate is dissolved in water, the whole solution will become purple, and the potassium manganate’s particles will be evenly distributed throughout the water.

Diffusion in gases

An example:

Perfume is sprayed in one corner of the room. Eventually, after some time, the gaseous particles of the perfume diffuse throughout the room, hence the scent of the perfume can be smelled in different corners of the room.

The effect of relative molecular mass on the rate of diffusion of gas

• At constant temperature, different particles with different relative molecular masses diffuse at different rates.

• The particle with a lower relative molecular mass diffuses faster than the one with a higher relative molecular mass. This is because it is lighter, hence it can travel faster

  (Hydrogen diffuses faster than any other gas as it has the lowest relative molecular mass.)