Define Diffusion.

Diffusion is a fundamental physical process in which particles, molecules, or substances move from an area of higher concentration to an area of lower concentration. It occurs in gases, liquids, and solids and is driven by the natural tendency of particles to spread out and achieve a state of equilibrium.

The key characteristics of diffusion include:

1. Random Motion: Particles move in random directions due to their kinetic energy. This random motion leads to a net movement from regions of higher concentration to lower concentration.
2. Passive Process: Diffusion is a passive process, meaning it does not require energy input. It is driven solely by the concentration gradient, where particles move down the concentration gradient to equalize the concentration throughout a medium.
3. Speed Factors: Diffusion rate depends on factors such as temperature (higher temperatures increase diffusion), the size and mass of the particles (smaller and lighter particles diffuse faster), and the nature of the medium (gases diffuse faster than liquids or solids).
4. Equilibrium: Diffusion continues until the concentration of the substance becomes uniform throughout the medium, resulting in a state of dynamic equilibrium where there is no net change in concentration over time.

Diffusion has numerous practical applications in fields like biology, chemistry, physics, and environmental science, and it plays a critical role in processes such as gas exchange in the respiratory system, the spread of aroma in cooking, and the dissolution of solutes in a solvent