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Isothermal Properties for Ammonia

Fluid Data

Isothermal Data for T = 25.000 C

Temperature (C)Pressure (bar)Density (kg/m3)Volume (m3/kg)Internal Energy (kJ/mol)Enthalpy (kJ/mol)Entropy (J/mol*K)Cv (J/mol*K)Cp (J/mol*K)Sound Spd. (m/s)Joule-Thomson (K/bar)Viscosity (uPa*s)Therm. Cond. (W/m*K)Phase

Auxiliary Data

Reference States, default for fluid

Additional fluid properties


Equation of state and auxiliary model

Tillner-Roth, R.; Harms-Watzenberg, F.; Baehr, H.D., Eine neue Fundamentalgleichung für Ammoniak., DKV-Tagungsbericht, 1993, 20, 167-181. [all data]

Auxiliary model

Ahrendts, J.; Baehr, H.D., The Thermodynamic Properties of Ammonia, VDI-Forsch., 1979, 596, 0. [all data]

Thermal conductivity

Tufeu, R.; Ivanov, D.Y.; Garrabos, Y.; Le Neindre, B., Thermal conductivity of ammonia in a large temperature and pressure range including the critical region, Ber. Bunsenges. Phys. Chem., 1984, 88, 422-427. [all data]

Viscosity and auxiliary model

Fenghour, A.; Wakeham, W.A.; Vesovic, V.; Watson, J.T.R.; Millat, J.; Vogel, E., The viscosity of ammonia, J. Phys. Chem. Ref. Data, 1995, 24, 1649-1667. [all data]

Surface tension

Durrant, A.A.; Pearson, T.G.; Robinson, P.L., Physical relationships amongst the hydrides of elements of the fifth group with special reference to association in these compounds, Journal of the Chemical Society (part 1), 1934, 730-735. [all data]

Surface tension

Laine, P., Kaeltemaschinen und -apparate: Pruefung von Kaeltemaschineteilen auf Dichtheit, Kaeltetechnik, 1953, 6, 173. [all data]

Surface tension

Stairs, R.A.; Sienko, M.J., Surface tension of ammonia and of solutions of alkalai halides in ammonia, J. Am. Chem. Soc., 1956, 78, 920-923. [all data]

Melting curve

Haar, L.; Gallagher, J.S., Thermodynamic Properties of Ammonia, J. Phys. Chem. Ref. Data, 1978, 7, 3, 635-792. [all data]

Additional Information

Equation of state

The uncertainties of the equation of state are 0.2% in density, 2% in heat capacity, and 2% in the speed of sound, except in the critical region. The uncertainty in vapor pressure is 0.2%.

Auxiliary model

Cp0/R = (2/9)*a3*Tr**(-1/3) - (15/4)*a4*Tr**(3/2) - (77/16)*a5*Tr**(7/4) where the ai are the original coefficients given by T-R and Tr = T/Tc

Thermal conductivity

A patch has been added to the Tufeu formulation to avoid infinite values of the thermal conductivity around the critical temperature at ANY density. The patch affects the region between 404.4 and 406.5 K and rho<9.6 or rho>18 mol/l.

The uncertainty in thermal conductivity is 2%.


The uncertainty varies from 0.5% for the viscosity of the dilute gas phase at moderate temperatures to about 5% for the viscosity at high pressures and temperatures.

Important Information About This Data

The data above are from an older version of the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP version 7). We will be updating our site to use the newer version (version 10) of this database in the future. Information on REFPROP version 10 can be found on theREFPROP web page. REFPROP version 10 includes additional data and features not available from this site.