Geology Reference
In-Depth Information
Enthalpy and Gibbs free energy of the substances presented here are obtained
either through the literature or the estimation methods described in Valero D. et al.
(2012). Remember also that the chemical exergy of the substance (b
chi
) in kJ/mol
is calculated with Eq. (9.29):
b
chi
= G
f
+
X
j
r
j;i
b
chj
where b
chj
is the standard chemical exergy of the elements that compose substance
i as shown in Table 9.1. The average enthalpy, Gibbs free energy and exergy of the
Earth's layers, can be expressed in mol=g by substituting x
i
with the molar fraction
i
for the i constituents of each sphere. Eq. (11.4) connects both properties through
the molecular weight of the sphere considered (MW
sphere
):
x
i
=
i
MW
sphere
(11.4)
In the next sections, the specific and global standard properties of the sub-
stances that compose the atmosphere, hydrosphere and upper continental crust are
calculated.
11.2.1 The thermodynamic properties of the atmosphere
Table 11.1 shows the standard thermodynamic properties of the substances con-
tained in the atmosphere (on a dry basis), according to the composition provided
in Sec. 5.3.1. Values for H
f i
and G
f i
are taken from Weast et al. (1986).
Table 11.1: Thermodynamic properties of the atmosphere. Values of H
0
fi
,
G
0
fi
, b
0
chi
in kJ/mol
H
f i
G
f i
b
chi
Substance
Formula
x
i
[-]
Nitrogen
N
2
7.81E-01
0.0
0.0
0.72
Oxygen
O
2
2.09E-01
0.0
0.0
3.97
Argon
Ar
9.34E-03
0.0
0.0
11.7
Carbon dioxide
CO
2
3.60E-04
-393.7
-394.4
19.9
Neon
Ne
1.82E-05
0.0
0.0
27.2
Helium
He
5.24E-06
0.0
0.0
30.4
Methane
CH
4
1.70E-06
-74.8
-50.8
831.7
Hydrogen
H
2
5.50E-07
0.0
0.0
236.1
Nitrogen oxides
NO
2
5.05E-07
33.2
51.3
55.7
Nitrous oxide
N
2
O
3.10E-07
82.1
104.2
106.9
Ozone (troposphere)
O
3
2.55E-07
142.7
163.3
169.2
Carbon monoxide
CO
1.25E-07
-137.2
-110.6
301.7
NMHC (assuming ethylene) C
2
H
4
1.25E-08
52.3
70.3
1363.0
Ozone (stratosphere)
O
3
5.25E-09
142.7
163.3
169.2
Continued on next page :::
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