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Experimental data for HI (Hydrogen iodide)

22 02 02 11 45
Other names
Hydriodic acid; Hydroiodic acid; hydrogen iodide;
INChI INChIKey SMILES IUPAC name
InChI=1S/HI/h1H XMBWDFGMSWQBCA-UHFFFAOYSA-N I hydrogen iodide
State Conformation
1Σ C*V
Enthalpy of formation (Hfg), Entropy, Integrated heat capacity (0 K to 298.15 K) (HH), Heat Capacity (Cp)
Property Value Uncertainty units Reference Comment
Hfg(298.15K) enthalpy of formation 26.50 0.10 kJ mol-1 CODATA
Hfg(0K) enthalpy of formation 28.68 0.10 kJ mol-1 CODATA
Entropy (298.15K) entropy 206.59   J K-1 mol-1 webbook
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 8.66   kJ mol-1 Gurvich
Heat Capacity (298.15K) heat capacity 29.16   J K-1 mol-1 Gurvich
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency Intensity Comment Description
Fundamental(cm-1) Harmonic(cm-1) Reference (km mol-1) unc. Reference
1 Σ 2230 2309 webbook      

Detailed diatomic data
ωe ωexe ωeye Be αe ZPE reference
2309.014 39.6435 -0.02 6.426365 0.16886 webbook

vibrational zero-point energy: 1114.8 cm-1 (from fundamental vibrations)
Calculated vibrational frequencies for HI (Hydrogen iodide).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  6.42637 6.42637 webbook

Calculated rotational constants for HI (Hydrogen iodide).
Product of moments of inertia moments of inertia
2.623199amu Å2   4.355992E-40gm cm2
Geometric Data
picture of Hydrogen iodide

Point Group C∞v


Internal coordinates
distances (r) in Å, angles (a) in degrees, dihedrals (d) in degrees
Description Value unc. Connectivity Reference Comment
Atom 1 Atom 2 Atom 3 Atom 4
rHI 1.609 0.000 1 2 NISTdiatomic re

Cartesians
Atom x (Å) y (Å) z (Å)
I1 0.0000 0.0000 0.0000
H2 0.0000 0.0000 1.6092

Atom - Atom Distances bond lengths
Distances in Å
  I1 H2
I1   1.6092
H2 1.6092  

Calculated geometries for HI (Hydrogen iodide).

Bond descriptions


Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-I 1

Connectivity
Atom 1 Atom 2
I1 H2
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1Σ

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
10.386 0.001     webbook

Proton Affinity (kJ mol-1)
Proton Affinity unc. Product reference comment
627.5   H2I+ webbook  
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
State Config State description Conf description Exp. min. Dipole (Debye) Reference comment Point Group Components
x y z total dipole quadrupole
1 1 1Σ C∞v True       0.448 NISTDiatomic ± 0.0005 μ0 C∞v 1 1
Experimental dipole measurement abbreviations: MW microwave; DT Dielectric with Temperature variation; DR Indirect (usually an upper limit); MB Molecular beam
Calculated electric dipole moments for HI (Hydrogen iodide).
Electric quadrupole moment quadrupole
State Config State description Conf description Exp. min. Quadrupole (D Å) Reference comment Point Group Components
xx yy zz dipole quadrupole
1 1 1Σ C∞v True       C∞v 1 1

Calculated electric quadrupole moments for HI (Hydrogen iodide).
Electric dipole polarizability (Å3) polarizability
alpha unc. Reference
5.453   1997Oln/Can:59

Calculated electric dipole polarizability for HI (Hydrogen iodide).

References
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squib reference DOI
1997Oln/Can:59 TN Olney, NM Cann, G Cooper, CE Brion, Absolute scale determination for photoabsorption spectra and the calculation of molecular properties using dipole sum-rules, Chem. Phys. 223 (1997) 59-98 10.1016/S0301-0104(97)00145-6
CODATA Cox, J.D.; Wagman, D.D.; Medvedev, V.A.CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989 10.1002/bbpc.19900940121
Gurvich Gurvich, L.V.; Veyts, I. V.; Alcock, C. B., Thermodynamic Properties of Individual Substances, Fouth Edition, Hemisphere Pub. Co., New York, 1989  
NISTdiatomic NIST Diatomic Spectral Database (www.physics.nist.gov/PhysRefData/MolSpec/Diatomic/index.html) 10.18434/T4T59X
webbook NIST Chemistry Webbook (http://webbook.nist.gov/chemistry) 10.18434/T4D303

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