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Diffusion is of fundamental importance in many disciplines of physics, chemistry, and biology. Some example applications of diffusion: Sintering to produce solid materials (powder metallurgy, production of ceramics) Chemical reactor design; Catalyst design in chemical industry; Steel can be diffused (e.g., with carbon or nitrogen) to modify its ...
With respect to molecular diffusion, dispersion occurs as a result of an unequal concentration of the introduced material throughout the bulk medium. When the dispersed material is first introduced into the bulk medium, the region at which it is introduced then has a higher concentration of that material than any other point in the bulk.
The concept of diffusion is widely used in many fields, including physics (particle diffusion), chemistry, biology, sociology, economics, statistics, data science, and finance (diffusion of people, ideas, data and price values). The central idea of diffusion, however, is common to all of these: a substance or collection undergoing diffusion ...
Molecular diffusion occurs in gases, liquids, and solids. Diffusion is a result of thermal motion of molecules. Usually, convection occurs as a result of the diffusion process. The rate at which diffusion occurs depends on the state of the molecules: it occurs at a high rate in gases, a slower rate in liquids, and an even slower rate in solids.
There are some notable similarities in equations for momentum, energy, and mass transfer [7] which can all be transported by diffusion, as illustrated by the following examples: Mass: the spreading and dissipation of odors in air is an example of mass diffusion. Energy: the conduction of heat in a solid material is an example of heat diffusion.
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Dialysis is the process used to change the matrix of molecules in a sample by differentiating molecules by the classification of size. [6] [7] It relies on diffusion, which is the random, thermal movement of molecules in solution (Brownian motion) that leads to the net movement of molecules from an area of higher concentration to a lower concentration until equilibrium is reached.
In chemical physics, atomic diffusion is a diffusion process whereby the random, thermally-activated movement of atoms in a solid results in the net transport of atoms. For example, helium atoms inside a balloon can diffuse through the wall of the balloon and escape, resulting in the balloon slowly deflating.