135
Ionic Interactions
4.3.1 uniformist (average) Models
Bernal and Fowler (1933), Pople (1951), Wall and Horning (1965), and Falk and Kell (1966)
were proponents of the uniformist model. The basic element of the uniformist view is that
no local domains exist in water with a different structure from that of any other arbitrarily
chosen element of water. In the process of averaging, the individual water molecule behaves
at any time much like any other water molecule is behaving. Bernal and Fowler’s (1933)
original model has been used and has worked well in many applications. Pople’s (1951)
treatment gave a far greater qualitative insight into the structure of water. Pople explained
the maximum density of liquid water as resulting from two opposing effects—increase in
volume caused by expansion of the lattice structure and a bending of the H bonds. Thus,
this model treats liquid water as an “ice- like” lattice with differences caused by the bending of bonds, not the breaking of bonds.
4.3.2 Mixture Models
The mixture models have received more notice over the years. We can divide the mixture
models into the following categories:
0 20 40 60 80 100
v (cm
3
)
0.99
1.00
1.01
1.02
1.03
1.04
1.05
4°C
Specific Volume
Temperature (°C)
Temperature (°C)
0 20 40 60 80 100
U (m s
–1
)
1400
1440
1480
1520
1560
Sound Speed
75°C
β × 10
6
(bar
–1
)
44
46
48
50
52
Compressibility
45°C
Temperature (°C)
0 20 40 60 80 100
Temperature (°C)
0 20 40 60 80 100
Cp (joules)
4.18
4.19
4.20
4.21
4.22
Specific Heat
30°C
Figure 4.6
The effects of temperature on the specific volume (1/density), sound speed, compressibility, and heat capacity
for water.
Ionic Interactions
4.3.1 uniformist (average) Models
Bernal and Fowler (1933), Pople (1951), Wall and Horning (1965), and Falk and Kell (1966)
were proponents of the uniformist model. The basic element of the uniformist view is that
no local domains exist in water with a different structure from that of any other arbitrarily
chosen element of water. In the process of averaging, the individual water molecule behaves
at any time much like any other water molecule is behaving. Bernal and Fowler’s (1933)
original model has been used and has worked well in many applications. Pople’s (1951)
treatment gave a far greater qualitative insight into the structure of water. Pople explained
the maximum density of liquid water as resulting from two opposing effects—increase in
volume caused by expansion of the lattice structure and a bending of the H bonds. Thus,
this model treats liquid water as an “ice- like” lattice with differences caused by the bending of bonds, not the breaking of bonds.
4.3.2 Mixture Models
The mixture models have received more notice over the years. We can divide the mixture
models into the following categories:
0 20 40 60 80 100
v (cm
3
)
0.99
1.00
1.01
1.02
1.03
1.04
1.05
4°C
Specific Volume
Temperature (°C)
Temperature (°C)
0 20 40 60 80 100
U (m s
–1
)
1400
1440
1480
1520
1560
Sound Speed
75°C
β × 10
6
(bar
–1
)
44
46
48
50
52
Compressibility
45°C
Temperature (°C)
0 20 40 60 80 100
Temperature (°C)
0 20 40 60 80 100
Cp (joules)
4.18
4.19
4.20
4.21
4.22
Specific Heat
30°C
Figure 4.6
The effects of temperature on the specific volume (1/density), sound speed, compressibility, and heat capacity
for water.