CHAPTER 10 . Equilibrium Analysis, the Ionic Medium Method and Activity Factors
269
and the other cations; A,nM is the virial coefficient representing the interactions between a specific cation and neutral species; ljIijk is the virial coefficient representing
interactions between ions i,j, k (where i and j are different anions and k is a cation or
when i and j are different cations and k is an anion). The parameters ljI and A, are assumed to be independent of ionic strength. The quantity F includes the Debye-Hiickel,
f~ and other terms as follows:
F = F + I,I,mcmaB~c + I,I,mcmc'l/J~c' + I,I,mamA~a'
(10.12)
c a e c'
a a'
where
F = -Aq, J JIk, + ~ln(1 + b[I:)l
11 + b 1m b
J
(10.13)
and ¢I and B' are the ionic strength derivatives of I/J and B, respectively (see below). B
and B' are equal to:
Z = I,mdZil
(10.14)
i
213(1) {
}
B Ma = f3~~ + a~a 1- (1 + aI1I2)exp(-aII/2) = f3~~ + f3U~g(aI1I2)
(10.15)
and
Ma = -2"2 1- (1 + aI 1I2 + -)exp(-aI I/2 ) = 13(1) g aI
B '
2f3i.Va{
a 2 1
}
'( 112)
aI
2
Ma
I
(10.16)
C ca and the virial coefficient I/Jij are defined as follows:
C
C
Ca=~
21ZcZa 111
2
C Ma = C~a
21ZcZa 111 2
(10.17)
I/Jij = eij+Eei/I)
(10.18)