CHAPTER 1 . Sea Water as an Electrolyte
Fig. 1.19. Correlation of the
molal volume and
compressibility of ions
40
20
0
,
(5
E
E - 20
~
' S.
-40
-60
o
o
o
23
_80L' __ ~ __ L-~ __ -L __ - L __ ~ __ L-~ __ ~
-140 - 120 - 100 -80 -00 -40 - 20
0
20
40
/(D x 1()4 (em] mol-' bar')
Log Y= _AZ2[1/2 / (1 + B[1I2)
(1.30)
where A = 0.51 and B = 0.33 at 25°C. The ion pairing model assumes that deviations from the
Debye-Hiickel theory are due to the formation of interactions between ions of an opposite
sign. The ion pairing model assumes that only the interactions between cations and anions are important in the solution and that these interactions can be strong enough to form
a new ion-paired species. The Friedman cluster expansion model attempts to consider
interactions of an opposite sign and those of the same sign (Fig. 1.20). The interactions
in a mixed electrolyte solution like sea water are accounted for by examining
the properties of single (NaCl) and binary electrolyte solutions with a common ion
(NaCl + MgCI2). This latter model has proved to be useful in estimating the properties of mixed
electrolyte solutions like sea water. The use of these methods is described in more detail in the
next section.
1.3
Estimating the Properties of Mixed Electrolytes
This is done by using the apparent molal properties (41) of the solution (Fig. 1.21). The
apparent molal property is related to the change that occurs when a salt is added to
water. The apparent molal property is defined by:
41 = f'..p / n = (P - pO) / n
(1.31)
where n is the number of moles or equivalents of added salt, P is the property of the
solution, and pO is the property of water. The apparent molal property for a mixed elec-
Fig. 1.19. Correlation of the
molal volume and
compressibility of ions
40
20
0
,
(5
E
E - 20
~
' S.
-40
-60
o
o
o
23
_80L' __ ~ __ L-~ __ -L __ - L __ ~ __ L-~ __ ~
-140 - 120 - 100 -80 -00 -40 - 20
0
20
40
/(D x 1()4 (em] mol-' bar')
Log Y= _AZ2[1/2 / (1 + B[1I2)
(1.30)
where A = 0.51 and B = 0.33 at 25°C. The ion pairing model assumes that deviations from the
Debye-Hiickel theory are due to the formation of interactions between ions of an opposite
sign. The ion pairing model assumes that only the interactions between cations and anions are important in the solution and that these interactions can be strong enough to form
a new ion-paired species. The Friedman cluster expansion model attempts to consider
interactions of an opposite sign and those of the same sign (Fig. 1.20). The interactions
in a mixed electrolyte solution like sea water are accounted for by examining
the properties of single (NaCl) and binary electrolyte solutions with a common ion
(NaCl + MgCI2). This latter model has proved to be useful in estimating the properties of mixed
electrolyte solutions like sea water. The use of these methods is described in more detail in the
next section.
1.3
Estimating the Properties of Mixed Electrolytes
This is done by using the apparent molal properties (41) of the solution (Fig. 1.21). The
apparent molal property is related to the change that occurs when a salt is added to
water. The apparent molal property is defined by:
41 = f'..p / n = (P - pO) / n
(1.31)
where n is the number of moles or equivalents of added salt, P is the property of the
solution, and pO is the property of water. The apparent molal property for a mixed elec-