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Experimental data for NH3 (Ammonia)

Other names
Ammonia; Ammonia gas; Ammonia, anhydrous; Anhydrous ammonia; Aromatic Ammonia, Vaporole; Nitro-Sil; Spirit of Hartshorn; azane;
State Conformation
1A1 C3V
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 -45.94 0.35 kJ mol-1 CODATA
Hfg(0K) enthalpy of formation -38.95 0.35 kJ mol-1 CODATA
Entropy (298.15K) entropy 192.77 0.05 J K-1 mol-1 CODATA
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 10.04 0.01 kJ mol-1 CODATA
Heat Capacity (298.15K) heat capacity 35.63   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 A1 3337   Shim 7.1 0.8 1983Koo/Vis:203 sym stretch
2 A1 950   Shim 138.0 6.0 1983Koo/Vis:203 sym. deform.
3 E 3444   Shim 4.3 0.7 1983Koo/Vis:203 deg. stretch
4 E 1627   Shim 28.2 0.5 1983Koo/Vis:203 deg. deform

vibrational zero-point energy: 7214.5 cm-1 (from fundamental vibrations)
Calculated vibrational frequencies for NH3 (Ammonia).
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
9.44430 9.44430 6.19600 1966Herzberg

Calculated rotational constants for NH3 (Ammonia).
Product of moments of inertia moments of inertia
8.668394amu3Å6   3.96923338173294E-119gm3 cm6
Geometric Data
picture of Ammonia

Point Group C3v

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
rNH 1.012   1 2 1966Herzberg
aHNH 106.67 2 1 3 1966Herzberg
aXNH 112.15 255 1 2 1966Herzberg from symmetry. X is on symmetry axis.

Atom x (Å) y (Å) z (Å)
N1 0.0000 0.0000 0.0000
H2 0.0000 -0.9377 -0.3816
H3 0.8121 0.4689 -0.3816
H4 -0.8121 0.4689 -0.3816

Atom - Atom Distances bond lengths
Distances in Å
  N1 H2 H3 H4
N1   1.01241.01241.0124
H2 1.0124   1.62421.6242
H3 1.01241.6242   1.6242
H4 1.01241.62421.6242  

Calculated geometries for NH3 (Ammonia).

Experimental Bond Angles (degrees) from cartesians bond angles

atom1 atom2 atom3 angle         atom1 atom2 atom3 angle
H2 N1 H3 106.670 H2 N1 H4 106.670
H3 N1 H4 106.670

Bond descriptions

Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-N 3

Atom 1 Atom 2
N1 H2
N1 H3
N1 H4
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1   1A1
46136 1 1966Herzberg

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
10.070 0.020 10.820   webbook

Proton Affinity (kJ mol-1)
Proton Affinity unc. Product reference comment
853.6   NH4+ webbook  
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
Dipole (Debye) Reference comment
x y z total
      1.470 NSRDS-NBS10  

Calculated electric dipole moments for NH3 (Ammonia).
Electric quadrupole moment quadrupole
Quadrupole (D Å) Reference comment
xx yy zz
1.160 1.160 -2.320 1974Hel/Hel(II/6)

Calculated electric quadrupole moments for NH3 (Ammonia).
Electric dipole polarizability (Å3) polarizability
alpha unc. Reference
2.103   1997Oln/Can:59

Calculated electric dipole polarizability for NH3 (Ammonia).

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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 
1983Koo/Vis:203 Th Koops, T Visser, WMA Smit "Measurement and Interpretation of the Absolute Infrared Intensities of NH3 and ND3" Journal of Molecular Structure 96 (1983) 203-218 10.1016/0022-2860(83)90049-2
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  
NSRDS-NBS10 R. D. Nelson Jr., D. R. Lide, A. A. Maryott "Selected Values of electric dipole moments for molecules in the gas phase" NSRDS-NBS10, 1967 10.6028/NBS.NSRDS.10
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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