Table 9.3 Enthalpy of formation, Gibbs function of formation and absolute entropy at 25 °C and
1 atm
Substance
Formula
h
o
f (kJ/kmol)
g
o
f (kJ/kmol)
S
o (kJ/kmol-K)
Carbon
C(s)
0
0
5.74
Hydrogen
H 2 (g)
0
0
130.68
Nitrogen
N 2 (g)
0
0
191.61
Oxygen
O 2 (g)
0
0
205.04
Carbon monoxide
CO(g)
−110,530
−137,150
197.65
Carbon dioxide
CO 2 (g)
−393,520
−394,360
213.80
Water vapor
H 2 O(g)
−241,820
−228,690
188.83
Water
H 2 O(l)
−285,830
−237,180
69.92
Hydrogen peroxide
H 2 O 2 (g)
−136,310
−105,600
232.63
Ammonia
NH 3 (g)
−46,190
−16,590
192.33
Methane
CH 4 (g)
−74,850
−50,790
186.16
Acetylene
C 2 H 2 (g)
+226,730
+209,170
200.85
Ethylene
C 2 H 4 (g)
+52,280
+68,120
219.83
Ethane
C 2 H 6 (g)
−84,680
−32,890
229.49
Propylene
C 3 H 6 (g)
+20,410
+62,720
266.94
Propane
C 3 H 8 (g)
−103,850
−23,490
269.91
n-Butane
C 4 H 10 (g)
−126,150
−15,710
310.12
n-Octane
C 8 H 18 (g)
−208,450
+16,530
466.73
n-Octane
C 8 H 18 (l)
−249,950
+6,610
360.79
n-Dodecane
C 12 H 26 (g)
−291,010
+50,150
622.83
Benzene
C 6 H 6 (g)
+82,930
+129,660
269.20
Methyl alcohol
CH 3 OH(g)
−200,670
−162,000
239.70
Methyl alcohol
CH 3 OH(l)
−238,660
−166,360
126.80
Ethyl alcohol
C 2 H 5 OH(g)
−235,310
−168,570
282.59
Ethyl alcohol
C 2 H 5 OH(l)
−277,690
−174,890
160.70
Oxygen
O(g)
+249,190
+231,770
161.06
Hydrogen
H(g)
+218,000
+203,290
114.72
Nitrogen
N(g)
+472,650
+455,510
153.30
Hydroxyl
OH(g)
+39,460
+34,280
183.70
Source From JANAF, Thermochemical Tables (Midland, MI: Dow Chemical Co., 1971); Selected
Values of Chemical Thermodynamic Properties, NBS Technical Note 270-3, 1968; and API
Research Project 44 (Carnegle Press, 1953)
264
9 Applications to Special States of Thermodynamic Equilibrium …