preface to fifteenth edition

ELECTROLYTES, EMF, AND CHEMICAL EQUILIBRIUM 8.169
Conductance of an Electrolyte Solution
1 S
[
1]
R d
where S is the surface area of the electrode, or the mean cross-sectional area of the solution [m 2 ],
and d is the mean distance between the electrodes [m].
Equivalent Conductivity
1 2 1
[ · m · equiv ]
C
In the older literature, C is the concentration in equivalents per liter. The volume of the solution in
cubic centimeters per equivalent is equal to 1000/C, and 1000 /C, the units employed in Table
8.32 [ 1 ·cm 2 · equiv 1 ]. The formula unit used in expressing the concentration must be specified;
for example, NaCl, 1 ⁄2K2SO, 4 1 ⁄3LaCl 3.
The equivalent conductivityof an electrolyte is the sum of contributions of the individual ions.
At infinite dilution: c a, where c and a
are the ionic conductances of cations and anions,
respectively, at infinite dilution (Table 8.35).
Ionic Mobilityand Ionic Equivalent Conductivity
1 2 1
c Fuc and a Fu a [ · m · equiv ]
where F is the Faradayconstant, and u c , u a are the ionic mobilities [m 2 ·s 1 ·V 1 ].
F(u u ) ( )
c a c a
where is the degree of electrolytic dissociation, /. The electric mobility u of a species is the
magnitude of the velocityin an electric field [m · s 1 ] divided bythe magnitude of the strength of
the electric field E[V · m 1 ].
Ostwald Dilution Law
K d
2
C
1
where K d is the dissociation constant of the weak electrolyte. In general for an electrolyte which
yields n ions:
K d
C
(n1)
(n1)( )
Transference Numbers or Hittorf Transport Numbers
c
a
Tc Ta Tc Ta
1
Tc uc c
T u
c a c a
a a a
T
T
c c a a
n