Solution to Continuity Equation

FIGURE 10.2 Evaluation of diffusion coefficient from area/height plot. 

FIGURE 10.3 Evaluation of the diffusion coefficient from standard deviation. 

Values of the integral are tabulated in most mathematical function books, usually expressed in terms of z  

Both of these equations are called error functions. 

Einstein interpreted diffusion as being a result of the random thermal motion of molecules. Such a random motion is caused by fluctuations in pressure in a liquid. Thus, diffusion is closely related to Brownian motion. The Brownian motion consists of zigzag motion in aU directions. It is a random walk, as discussed in Chapter 5, and is described by the parameter (x ), the square mean displacement. The equation of motion in one dimension for the Brownian motion of a particle in solution is given by 

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