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Thermodynamic reference states.

Integrated Heat Capacity (H(298)-H(0)) in kJ mol-1
Element Reference State H(298)-H(0) unc.
H H2, g 8.468 0.001
D D2, g 8.569  
He He, g 6.197  
Li Li, cr 4.632 0.040
Be Be, cr 1.950 0.020
B B, cr 1.222 0.008
C C, cr graphite 1.050 0.020
N N2, g 8.670 0.001
O O2, g 8.680 0.002
F F2, g 8.825 0.001
Ne Ne, g 6.197  
Na Na, cr 6.460 0.020
Mg Mg, cr 4.998 0.030
Al Al, cr 4.540 0.020
Si Si, cr 3.217 0.008
P P, cr white 5.360 0.002
S S, cr rhombic 4.412 0.006
Cl Cl2, g 9.181 0.001
Ar Ar, g 6.197  
K K, cr 7.082  
Ti Ti, cr 4.824 0.015
Cu Cu, cr 5.004 0.008
Br Br2, l 24.520 0.010
Kr Kr, g 6.197  
Xe Xe, g 6.197  
Data from CODATA
Cox, J.D.; Wagman, D.D.; Medvedev, V.A.CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989

For gas-phase species with well defined enthalpies of formation that are useful in calculating reactions see section VII.C.2 Species with well-known enthalpies of formation


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