Welcome to the NIST Chemistry WebBook

The NIST Chemistry WebBook provides access to data compiled and distributed by NIST under the Standard Reference Data Program.

The NIST Chemistry WebBook contains:

Thermochemical data for over 7000 organic and small inorganic compounds:
- Enthalpy of formation
- Enthalpy of combustion
- Heat capacity
- Entropy
- Phase transition enthalpies and temperatures
- Vapor pressure
Reaction thermochemistry data for over 8000 reactions.
- Enthalpy of reaction
- Free energy of reaction
IR spectra for over 16,000 compounds.
Mass spectra for over 33,000 compounds.
UV/Vis spectra for over 1600 compounds.
Gas chromatography data for over 27,000 compounds.
Electronic and vibrational spectra for over 5000 compounds.
Constants of diatomic molecules (spectroscopic data) for over 600 compounds.
Ion energetics data for over 16,000 compounds:
- Ionization energy
- Appearance energy
- Electron affinity
- Proton affinity
- Gas basicity
- Cluster ion binding energies
Thermophysical property data for 74 fluids:
- Densityspecific volume
- Heat capacity at constant pressure (C_p)
- Heat capacity at constant volume (C_v)
- Enthalpy
- Internal energy
- Entropy
- Viscosity
- Thermal conductivity
- Joule-Thomson coefficient
- Surface tension (saturation curve only)
- Sound speed

You can search for data on specific compounds in the Chemistry WebBook based on namechemical formulaCAS registry number, molecular weightchemical structureor selected ion energetics and spectral properties.

NIST reserves the right to charge for access to this database in the future.

The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. HoweverNIST makes no warranties to that effectand NIST shall not be liable for any damage that may result from errors or omissions in the Database.

Click here to enter the NIST Chemistry WebBook.