The particle theory can also be used to explain diffusion. Diffusion is the spreading out of particles to fill the space they are in, until there is an even concentration of particles in the space.
For example, if there is a diffuser releasing air freshener in one corner of a room, your nose will pick up the smell in another part of the room. The smell of the air freshener spreads throughout the room even though you cannot see it in the air.
Diffusion occurs mainly in liquids and gases. Diffusion happens by itself. You do not need to mix or stir the substances. Temperature and the size of the particles affect the speed of diffusion.
? TEST TUBE
4. Fig. 14.8 (A) shows the particles as soon as a roast chicken is taken out of the oven. The blue particles represent the particles you can smell from the chicken, the white ones represent the air particles. Copy and complete Fig. 14.8 (B) to show how the smell of the food reaches your nose.