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is the gradient, i.e., rate of change with position, of the logarithm of the salt concentration, which is equivalent to the rate of change of the salt concentration, divided by the salt concentration – it is effectively one over the distance over which the concentration decreases by a factor of e. The above equation is approximate, and ...
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 ...
Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules. The result of diffusion is a gradual mixing of material such that the ...
The mole fraction, the molar concentration, and the partial pressure of both gases involved in equimolar counterdiffusion vary linearly. These relationships can be found in the following equations expressing the molar flow rates for each species, A and B, for a one-dimensional flow through a channel with no homogeneous chemical reactions:
In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (a fluid such as a liquid, gas, or vapor) through a solid.It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. [1]
This unequal distribution results in a concentration gradient that drives the dispersion of particles in the medium so that the concentration is constant across the entire bulk. With respect to convection, variations in velocity between flow paths in the bulk facilitate the distribution of the dispersed material into the medium.
Flow injection analysis (FIA) was first described by Ruzicka and Hansen in Denmark in 1974 and Stewart and coworkers in United States in 1979. FIA is a popular, simple, rapid, and versatile technique which is a well-established position in modern analytical chemistry, and widespread application in quantitative chemical analysis. [6]
Dependence on a total concentration n for a given temperature has always the same character, 1/n. In applications to gas dynamics, the diffusion flux and the bulk flow should be joined in one system of transport equations. The bulk flow describes the mass transfer. Its velocity V is the mass average velocity. It is defined through the momentum ...