Diffusion

Diffusion is a process which occurs when particles spread. They move from a region with higher concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. We can observe this in gases and particles dissolved in solutions. Particles diffuse down a concentration gradient. We could find a lot of examples of diffusion from daily life. We can smell perfume because it diffuses into the air and makes its way into our nose. A teabag placed in a cup of hot water will diffuse into the water, cigarette smoke diffuses into the air, etc.