NIST-JANAF Thermochemical Tables. III. Diatomic Hydrogen Halide ...

2.2. Hydrogen Chloride
Hydrogen chloride HCl Ideal gas M r36.460 94
fH o (0 K)92.1250.10 kJ•mol 1
S o (298.15 K)186.9010.005 J•K 1 •mol 1 fH o (298.15 K)92.310.10 kJ•mol 1
Molecular constants
Ground electronic state: X
Symmetry number: 1
1 Energy: X0 cm1 Quantum weight: gX1 EG vG 0F
Vibrational and rotational levels cm 1
v G vG 0 B v v G vG 0 B v
0 0 10.43552 10 24193.84 7.394749
1 2885.36 10.13171 11 26026.77 7.062304
2 5666.79 9.830326 12 27741.70 6.714696
3 8345.05 9.530733 13 29332.42 6.344519
4 10920.63 9.232105 14 30790.40 5.945010
5 13393.64 8.933706 15 32104.69 5.503231
6 15763.84 8.633476 16 33260.68 5.008014
7 18030.53 8.333761 17 34238.36 4.416872
8 20192.66 8.026480 18 35015.76 3.937957
9 22247.99 7.714602
F vB vZD vZ 2 H vZ 3 L vZ 4 L vZ 4 2 /H vZ 3 L vZ 4
D v5.310 70610 4 7.045 08110 6 Y 1.609 80110 7 Y 2 3.194 90810 8 Y 3 6.009 05310 9 Y 4 5.388 955
10 10 Y 5
H v1.694 80510 8 5.405 88510 10 Y 3.583 47310 11 Y 2
L v5.917 30710 12 where ZJJ1, Y v1/2
r e1.274 5610.000 001 Å
2.2.1. Enthalpy of Formation
The enthalpy of formation of hydrogen chloride, HCl, was
recommended by CODATA-ICSU 1 and is based on the results
of measurements of enthalpy of the reaction of hydrogen
with chlorine by Rossini, 2 Roth and Richter, 3 Wartenberg
and Hanish, 4 Lacher et al., 5 Faita et al., 6 Cerquetti et al., 7
and King and Armstrong. 8 The value for the dissociation
energy,
D0H 35Cl427.7680.010 kJ•mol1 35 7598 cm1 ,
corresponds to the selected value of fH o (HCl,g).
2.2.2. Heat Capacity and Entropy
These are calculated by direct summation over the
vibration–rotation levels of the ground electronic state. The
information on the vibration–rotation levels of HCl in the
ground X 1 state was obtained from the rotational analyses
of vibration–rotation bands, 9–43 microwave spectra, 44–54
NIST-JANAF THERMOCHEMICAL TABLES
927
CARS spectrum, 55
and the electronic transition, 56,57
B 1 – X 1 . The vibration–rotation spectrum of HCl was
investigated also in low-temperature matrices. 63–66 The potential
energy curve for the ground state derived from experimental
data was studied in numerous other works. 38,58–62
The adopted constants were selected from the following
works. The constants for v3 were obtained by Le Blanc
et al., 41 who included pure rotational data by Rinsland
et al. 40 in their treatment. G0(v) for 4v17 were derived
by Coxon and Roychowdhury 57 from the analysis of the
B 1 – X 1 transition (7v17) and for 4v7 were
recalculated from data by Coxon and Ogilvie. 38 The rotational
constants for 7v17 were also taken from Coxon
and Roychowdhury. 57 The rotational constants for 4v6
were taken from work by Clayton et al. 39 The rotational constants
for v1, obtained by De Natale et al. 53 and for v
7 by Reddy 36 agree well with those adopted here. 63–66
The selected experimental data for H35Cl were included in
the procedure described in Gurvich et al. 107 pp. 24–32. The
fitting procedure provided the convergence of the vibrational
J. Phys. Chem. Ref. Data, Vol. 33, No. 3, 2004