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Experimental data for H2O (Water)

Other names
Dihydrogen oxide; Distilled water; Ice; Water vapor; Water; oxidane;
State Conformation
1A1 C2V
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 -241.81 0.03 kJ mol-1 2006Rus/Pin:6592
Hfg(0K) enthalpy of formation -238.90 0.03 kJ mol-1 2006Rus/Pin:6592
Entropy (298.15K) entropy 188.84 0.01 J K-1 mol-1 CODATA
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 9.90 0.00 kJ mol-1 CODATA
Heat Capacity (298.15K) heat capacity 33.60   J K-1 mol-1 CODATA
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency (cm-1) Frequency Reference Intensity (km mol-1) Int. unc. Intensity Reference Comment
1 A1 3657 Shim 2.9   1992Cul/Lie:502
2 A1 1595 Shim 62.5   1992Cul/Lie:502
3 B2 3756 1979HUB/HER 41.7    

vibrational zero-point energy: 4504.0 cm-1
Calculated vibrational frequencies for H2O (Water).
Gas-phase IR spectra can be found in the NIST Chemistry Webbook here.
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
27.87700 14.51200 9.28500 1966Herzberg

Calculated rotational constants for H2O (Water).
Product of moments of inertia moments of inertia
1.275365amu3Å6   5.83985896432972E-120gm3 cm6
Geometric Data
picture of Water

Point Group

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
rOH 0.958 0.000 1 2 1979Hoy/Bun:1 re
aHOH 104.4776 0.0019 2 1 3 1979Hoy/Bun:1 equilibrium

Atom x (Å) y (Å) z (Å)
O1 0.0000 0.0000 0.1173
H2 0.0000 0.7572 -0.4692
H3 0.0000 -0.7572 -0.4692

Atom - Atom Distances bond lengths
Distances in Å
  O1 H2 H3
O1   0.95780.9578
H2 0.9578   1.5144
H3 0.95781.5144  

Calculated geometries for H2O (Water).

Experimental Bond Angles (degrees) from cartesians bond angles

atom1 atom2 atom3 angle
H2 O1 H3 104.478

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-O 2

Atom 1 Atom 2
O1 H2
O1 H3
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1A1
53800 1 1966Herzberg

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
12.621 0.002     webbook

Proton Affinity (kJ mol-1)
Proton Affinity unc. reference comment
691.0   webbook  
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
Dipole (Debye) Reference comment
1.855 NISTtriatomic +-0.0004

Calculated electric dipole moments for H2O (Water).
Electric quadrupole moment quadrupole
Quadrupole (D Å) Reference comment
xx yy zz
-2.500 2.630 -0.130 1974Hel/Hel(II/6) aa=2.63+-0.02 bb=-0.13+-E28 cc=-2.5+-0.02

Calculated electric quadrupole moments for H2O (Water).
Electric dipole polarizability (Å3) polarizability
alpha unc. Reference
1.501   1997Oln/Can:59

Calculated electric dipole polarizability for H2O (Water).

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squib reference DOI
1966Herzberg Herzberg, G., Electronic spectra and electronic structure of polyatomic molecules,Van Nostrand,New York, 1966  
1974Hel/Hel(II/6) Hellwege, KH and AM Hellwege (eds.). Landolt-Bornstein: Group II: Volume 6 Molecular Constants from Microwave, Molecular Beam, and Electron Spin Resonance Spectroscopy Springer-Verlag. Berlin. 1974. 10.1007/b19951 
1979Hoy/Bun:1 AR Hoy, PR Bunker, "A precise Solution of the Rotation Beninding Schrodinger Equation for a Triatomic Molecule with Application to the Water Molecule" J. Molecular Spectroscopy 74, 1-8, 1979 10.1016/0022-2852(79)90019-5
1979HUB/HER Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules,, Van Nostrand Reinhold Co., 1979 10.1007/978-1-4757-0961-2_2 
1992Cul/Lie:502 F Culot, J Lievin "Ab initio Calculation of Vibrational Dipole Moment Matrix Elements. II. The Water Molecule as a Polyatomic Test Case" Physica Scripta 46, 502-517, 1992 10.1088/0031-8949/46/6/004
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
2006Rus/Pin:6592 B Ruscic, RE Pinzon, ML Morton, NK Srinivasan, M-C Su, JW Sutherland, JV Michael "Active Thermochemical Tables: Accurate Enthalpy of Formation of Hydroperoxyl Radical, HO2" J. Phys. Chem. A 2006, 110, 6592-6601 10.1021/jp056311j
CODATA Cox, J.D.; Wagman, D.D.; Medvedev, V.A.CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989 10.1002/bbpc.19900940121
NISTtriatomic NIST Triatomic Spectral Database ( 10.18434/T4DW2S
Shim Shimanouchi, T. , Tables of Molecular Vibrational Frequencies, Consolidated Volume 1, NSRDS NBS-39 10.6028/NBS.NSRDS.39
webbook NIST Chemistry Webbook ( 10.18434/T4D303

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