Geology Reference
In-Depth Information
Table 11.3: Thermodynamic properties of average rivers. Values in kJ/mol. -
continued from previous page.
H
f i
b
chi
Substance
x
i
[-]
G
f i
NO3
2.90E-07
-207.5
-111.3
-105.1
Fe
2+
2.16E-07
-89.2
-78.9
297.9
SUM
1.00
The average standard enthalpy, Gibbs free energy and chemical exergy of rivers
(rw) are then:
(H
0
f
)
rw
= 286:0 kJ/mol
(G
0
f
)
rw
= 237:2 kJ/mol
(
b
0
ch
)
rw
= 0:79 kJ/mol
The average standard properties of glacial runoff, obtained from the composition
provided in Sec. 5.4.3.1, are given in Table 11.4.
Table 11.4: Thermodynamic properties of glacial runoff. Values in kJ/mol
H
f i
G
f i
b
chi
Substance
x
i
[-]
H
2
O
1.00E+00
-286.0
-237.2
0.79
Na
+
1.44E-05
-240.2
-261.9
74.6
HCO3
1.42E-05
-692.3
-586.9
-52.9
Ca
+2
5.71E-06
-543.1
-553.5
170.0
SO4
2
5.13E-06
-909.7
-774.5
-129.8
Cl
3.92E-06
-167.2
-131.0
-69.2
Mg
+2
1.92E-06
-467.1
-454.8
174.6
K
+
9.13E-07
-252.5
-283.3
83.2
SUM
1.00
The average standard enthalpy, Gibbs free energy and chemical exergy of glacial
runoff (gl) are:
(H
0
f
)
gl
= 286:0 kJ/mol
(G
f
)
gl
= 237:2 kJ/mol
(b
0
ch
)
gl
= 0:79 kJ/mol
Since the composition of river water and glacial runoff are almost the same,
similar thermochemical properties were expected, as corroborated by the figures
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