When we intermix a drop of ink with pure water, we notice within a certain time that ink completely blends with water (water is entirely coloured). We notice something similar when the odour of a perfume spreads all over the room even though we sprayed it on one spot only.
The both phenomena can be explained by DIFFUSION.
Diffusion is intermixing of fluids because of a constant disordered motion of molecules. Because the molecules of a fluid move in a constant disorder, the two lines of at first separated molecules can intermix completely. Because the intensity of a molecule motion depends upon the temperature of a substance, the diffusion is intensified at higher temperatures.
