Page 37 - Introduction to Colloid and Surface Chemistry

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 ine _ kT dc
d
— --— - -—— (2.12)
dr / dx fc dx ^
Since

dm , dx
™_ nuvKV :,-: m , ™' £\ /"* M ,_ Trrnmm
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/6injaN A - i.e.
l/!
D oc l/m , 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