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Function Repository Resource:

 AcentricFactor

Source Notebook

Estimate the acentric factor of a substance

Contributed by: Jan Mangaldan

ResourceFunction["AcentricFactor"][entity]

gives the acentric factor ω of the substance represented by entity.

ResourceFunction["AcentricFactor"][assoc]

uses the association assoc to look up properties needed to compute the acentric factor.

Details and Options

The acentric factor, introduced by Pitzer in 1955, is a measure of how far the molecule of a substance deviates from a spherical shape. It is often used in equations for computing various properties of fluids (gases and liquids).
The acentric factor is defined to be ω=-(Psat/Pc)-1, where Psat is the saturated vapor pressure of a substance at the temperature 0.7Tc, and Pc and Tc are, respectively, the critical pressure and temperature.
In ResourceFunction["AcentricFactor"][assoc], assoc must be given as an association containing the following elements:
"BoilingPoint"boiling point (at normal atmospheric pressure)
“CriticalPressure”critical pressure
"CriticalTemperature"critical temperature
ResourceFunction["AcentricFactor"] supports a Method option. Possible settings include:
"CDJ"method of Chen, Dinivahi and Jeng
"AmbroseWalton"method of Ambrose and Walton
"LeeKessler"method of Lee and Kessler

Examples

Basic Examples (1) 

Compute the acentric factor of nitrogen:

In[1]:=
ResourceFunction["AcentricFactor"][ Entity["Chemical", "MolecularNitrogen"]]
Out[1]=

Scope (1) 

Compute the acentric factor for Freon C-318 by supplying explicit values for its physical properties:

In[2]:=
ResourceFunction[ "AcentricFactor"][<| "BoilingPoint" -> Quantity[-6.04, "DegreesCelsius"], "CriticalTemperature" -> Quantity[115.23, "DegreesCelsius"], "CriticalPressure" -> Quantity[2777., "Kilopascals"]|>]
Out[2]=

Options (1) 

Method (1) 

Specify various methods for the acentric factor:

In[3]:=
Table[met -> ResourceFunction["AcentricFactor"][Entity["Chemical", "Ethane"], Method -> met], {met, {"CDJ", "AmbroseWalton", "LeeKessler"}}]
Out[3]=

Applications (2) 

Compute the acentric factor for a gas mixture that is 70% nitrogen and 30% oxygen by weight using a mixing rule:

In[4]:=
(* mole fractions *) molFrac = Normalize[{Quantity[0.7, "Grams"], Quantity[0.3, "Grams"]}/{Entity["Chemical", "MolecularNitrogen"][ EntityProperty["Chemical", "MolarMass"]], Entity["Chemical", "MolecularOxygen"][ EntityProperty["Chemical", "MolarMass"]]}, Total]; molFrac . {ResourceFunction["AcentricFactor"][ Entity["Chemical", "MolecularNitrogen"]], ResourceFunction["AcentricFactor"][ Entity["Chemical", "MolecularOxygen"]]}
Out[5]=

Use the resource function JobackEstimate to estimate physical properties of tetrafluoroethylene, the monomer of Teflon:

In[6]:=
assoc = ResourceFunction["JobackEstimate"][ Molecule[{"F", "C", "F", "C", "F", "F"}, { Bond[{1, 2}, "Single"], Bond[{2, 3}, "Single"], Bond[{2, 4}, "Double"], Bond[{4, 5}, "Single"], Bond[{4, 6}, "Single"]}, {}], {"NormalBoilingPoint", "CriticalPressure", "CriticalTemperature"}] // KeyMap[Replace["NormalBoilingPoint" -> "BoilingPoint"]]
Out[6]=

Use these estimated properties to estimate the acentric factor:

In[7]:=
ResourceFunction["AcentricFactor"][assoc]
Out[7]=

Compare with the acentric factor calculated from its actual physical properties:

In[8]:=
ResourceFunction["AcentricFactor"][ Entity["Chemical", "Tetrafluoroethylene"]]
Out[8]=

Requirements

Wolfram Language 12.3 (May 2021) or above

Version History

  • 1.0.0 – 03 January 2024

Source Metadata

  • Citation:
    • Ambrose D., Walton J., "Vapour pressures up to their critical temperatures of normal alkanes and 1-alkanols." Pure and Applied Chemistry, vol. 61, no. 8, 1395–1403, 1989.
      DOI: 10.1351/pac198961081395
    • Chen D.H., Dinivahi M.V., Jeng C.Y., "New acentric factor correlation based on the Antoine equation." Industrial & Engineering Chemistry Research, vol. 32, no. 1, 241–244, 1993.
      DOI: 10.1021/ie00013a034
    • Lee B.I., Kessler M.G., "A generalized thermodynamic correlation based on three-parameter corresponding states." AIChE Journal, vol. 21, no. 3, 510–527, 1975.
      DOI: 10.1002/aic.690210313
    • Pitzer K.S., "The Volumetric and Thermodynamic Properties of Fluids. I. Theoretical Basis and Virial Coefficients." Journal of the American Chemical Society, vol. 77, no. 13, 3427–3433, 1955.
      DOI: 10.1002/aic.690210313

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