92168.pdf

28 Kinetic properties

Therefore, combining equations (2.10) and (2.11),

x = (20^ (2.4)

Diffusion equation (2.5)

The work done in moving a particle through a distance dx against a

frictional resistance to motion f(dx/dt) can be equated with the

resulting change in chemical potential given by the expression

dp = kT d In c

dx_

dt

Therefore,

dx _ kT dine _ kT dc

— --— - -—— (2.12)

dr / dx fc dx ^

Since

™_ nuvKVdm:,-:m, ™' , £\ /"* M,_Trrnmm dx

dt dt

then combining this expression with equation (2.8) gives

c =D (2.13)

dr dx

Therefore, combining equations (2.12) and (2.13),

For a system containing spherical particles, D = RT/6injaNA - i.e.
D oc l/ml/!, where m is the particle mass. For systems containing
asymmetric particles, D is correspondingly smaller (see Table 2.3).
Since D = k77/, the ratio D/D(} (where D is the experimental
diffusion coefficient and D 0 is the diffusion coefficient of a system
containing the equivalent unsolvated spheres) is equal to the