Critical Properties (chemicals.critical)¶

This module contains lookup functions for critical temperature, critical pressure, critical volume, and critical compressibility factors. It also includes a few relationships between the critical properties, and a variety of critical mixture property estimation routines.

For reporting bugs, adding feature requests, or submitting pull requests, please use the GitHub issue tracker.

Critical Temperature
Critical Pressure
Critical Volume
Critical Compressibility Factor
Critical Property Relationships
Critical Temperature of Mixtures
Critical Volume of Mixtures

Critical Temperature ¶

chemicals.critical.Tc(CASRN, method=None)[source]¶

This function handles the retrieval of a chemical’s critical temperature. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Function has data for approximately 26000 chemicals.

Parameters

CASRNstr: CASRN [-]

Returns

Tcfloat: Critical temperature, [K]

Other Parameters

methodstr, optional: The method name to use. Accepted methods are ‘IUPAC’, ‘MATTHEWS’, ‘CRC’, ‘PD’, ‘WEBBOOK’, ‘PSRK’, ‘PINAMARTINES’, ‘YAWS’, ‘WILSON_JASPERSON’, ‘JOBACK’, ‘HEOS’. All valid values are also held in the list Tc_all_methods.

See also

Tc_methods

Notes

The available sources are as follows:

‘IUPAC’, a series of critically evaluated experimental datum for organic compounds in [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], and [12].

‘MATTHEWS’, a series of critically evaluated data for inorganic compounds in [13].

‘CRC’, a compillation of critically evaluated data by the TRC as published in [14].

‘PSRK’, a compillation of experimental and estimated data published in [15].

‘PD’, an older compillation of data published in [16]

‘YAWS’, a large compillation of data from a variety of sources; no data points are sourced in the work of [17].

‘WEBBOOK’, a NIST resource [18] containing mostly experimental and averaged values

‘JOBACK’, an estimation method for organic substances in [19]

‘WILSON_JASPERSON’, an estimation method in [21]

‘PINAMARTINES’, a series of values in the supporting material of [20]

‘HEOS’, a series of values from the NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids (and other high-precision fundamental equations of state)

References

1: Ambrose, Douglas, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 1. An Introductory Survey.” Journal of Chemical & Engineering Data 41, no. 1 (January 1, 1996): 154-154. doi:10.1021/je950378q.
2: Ambrose, Douglas, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 2. Normal Alkanes.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 531-46. doi:10.1021/je00019a001.
3: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 3. Aromatic Hydrocarbons.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 547-58. doi:10.1021/je00019a002.
4: Gude, Michael, and Amyn S. Teja. “Vapor-Liquid Critical Properties of Elements and Compounds. 4. Aliphatic Alkanols.” Journal of Chemical & Engineering Data 40, no. 5 (September 1, 1995): 1025-36. doi:10.1021/je00021a001.
5: Daubert, Thomas E. “Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes.” Journal of Chemical & Engineering Data 41, no. 3 (January 1, 1996): 365-72. doi:10.1021/je9501548.
6: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons.” Journal of Chemical & Engineering Data 41, no. 4 (January 1, 1996): 645-56. doi:10.1021/je9501999.
7: Kudchadker, Arvind P., Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 7. Oxygen Compounds Other Than Alkanols and Cycloalkanols.” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 457-79. doi:10.1021/je0001680.
8: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 8. Organic Sulfur, Silicon, and Tin Compounds (C + H + S, Si, and Sn).” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 480-85. doi:10.1021/je000210r.
9: Marsh, Kenneth N., Colin L. Young, David W. Morton, Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 9. Organic Compounds Containing Nitrogen.” Journal of Chemical & Engineering Data 51, no. 2 (March 1, 2006): 305-14. doi:10.1021/je050221q.
10: Marsh, Kenneth N., Alan Abramson, Douglas Ambrose, David W. Morton, Eugene Nikitin, Constantine Tsonopoulos, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 10. Organic Compounds Containing Halogens.” Journal of Chemical & Engineering Data 52, no. 5 (September 1, 2007): 1509-38. doi:10.1021/je700336g.
11: Ambrose, Douglas, Constantine Tsonopoulos, and Eugene D. Nikitin. “Vapor-Liquid Critical Properties of Elements and Compounds. 11. Organic Compounds Containing B + O; Halogens + N, + O, + O + S, + S, + Si; N + O; and O + S, + Si.” Journal of Chemical & Engineering Data 54, no. 3 (March 12, 2009): 669-89. doi:10.1021/je800580z.
12: Ambrose, Douglas, Constantine Tsonopoulos, Eugene D. Nikitin, David W. Morton, and Kenneth N. Marsh. “Vapor-Liquid Critical Properties of Elements and Compounds. 12. Review of Recent Data for Hydrocarbons and Non-Hydrocarbons.” Journal of Chemical & Engineering Data, October 5, 2015, 151005081500002. doi:10.1021/acs.jced.5b00571.
13: Mathews, Joseph F. “Critical Constants of Inorganic Substances.” Chemical Reviews 72, no. 1 (February 1, 1972): 71-100. doi:10.1021/cr60275a004.
14: Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
15: Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and Jürgen Gmehling. “PSRK Group Contribution Equation of State: Comprehensive Revision and Extension IV, Including Critical Constants and A-Function Parameters for 1000 Components.” Fluid Phase Equilibria 227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
16: Passut, Charles A., and Ronald P. Danner. “Acentric Factor. A Valuable Correlating Parameter for the Properties of Hydrocarbons.” Industrial & Engineering Chemistry Process Design and Development 12, no. 3 (July 1, 1973): 365-68. doi:10.1021/i260047a026.
17: Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.
18: Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
19: Joback, K.G., and R.C. Reid. “Estimation of Pure-Component Properties from Group-Contributions.” Chemical Engineering Communications 57, no. 1-6 (July 1, 1987): 233-43. doi:10.1080/00986448708960487.
20: Piña-Martinez, Andrés, Romain Privat, and Jean-Noël Jaubert. “Use of 300,000 Pseudo-Experimental Data over 1800 Pure Fluids to Assess the Performance of Four Cubic Equations of State: SRK, PR, Tc-RK, and Tc-PR.” AIChE Journal n/a, no. n/a (n.d.): e17518. https://doi.org/10.1002/aic.17518.
21: Wilson, G. M., and L. V. Jasperson. “Critical Constants Tc, Pc, Estimation Based on Zero, First and Second Order Methods.” In Proceedings of the AIChE Spring Meeting, 21, 1996.
22: Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.

Examples

>>> Tc(CASRN='64-17-5')
514.71

chemicals.critical.Tc_methods(CASRN)[source]¶

Return all methods available to obtain the critical temperature for the desired chemical.

Parameters

CASRNstr: CASRN, [-]

Returns

methodslist[str]: Methods which can be used to obtain Tc with the given inputs.

See also

Tc

chemicals.critical.Tc_all_methods = ('HEOS', 'IUPAC', 'MATTHEWS', 'CRC', 'PD', 'WEBBOOK', 'PSRK', 'PINAMARTINES', 'YAWS', 'WILSON_JASPERSON', 'JOBACK')¶: Tuple of method name keys. See the Tc for the actual references

chemicals.critical.Tc_all_method_types = {'CRC': 'PROCESSED_EXPERIMENTAL', 'HEOS': 'EXPERIMENTAL_REVIEW', 'IUPAC': 'EXPERIMENTAL_REVIEW', 'JOBACK': 'PREDICTED_GC', 'MATTHEWS': 'EXPERIMENTAL_COMPILATION', 'PD': 'EXPERIMENTAL_COMPILATION_SECONDARY', 'PINAMARTINES': 'PROCESSED_EXPERIMENTAL_PREDICTED_SECONDARY', 'PSRK': 'PROCESSED_EXPERIMENTAL_PREDICTED', 'WEBBOOK': 'PROCESSED_EXPERIMENTAL', 'WILSON_JASPERSON': 'PREDICTED_GC', 'YAWS': 'PROCESSED_EXPERIMENTAL_PREDICTED'}¶

Critical Pressure ¶

chemicals.critical.Pc(CASRN, method=None)[source]¶

This function handles the retrieval of a chemical’s critical pressure. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Function has data for approximately 26000 chemicals.

Parameters

CASRNstr: CASRN [-]

Returns

Pcfloat: Critical pressure, [Pa]

Other Parameters

methodstr, optional: The method name to use. Accepted methods are ‘IUPAC’, ‘MATTHEWS’, ‘CRC’, ‘PD’, ‘WEBBOOK’, ‘PSRK’, ‘PINAMARTINES’, ‘YAWS’, ‘WILSON_JASPERSON’, ‘JOBACK’, ‘HEOS’. All valid values are also held in the list Pc_all_methods.

See also

Pc_methods

Notes

The available sources are as follows:

‘IUPAC’, a series of critically evaluated experimental datum for organic compounds in [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], and [12].

‘MATTHEWS’, a series of critically evaluated data for inorganic compounds in [13].

‘CRC’, a compillation of critically evaluated data by the TRC as published in [14].

‘PSRK’, a compillation of experimental and estimated data published in [15].

‘PD’, an older compillation of data published in [16]

‘YAWS’, a large compillation of data from a variety of sources; no data points are sourced in the work of [17].

‘WEBBOOK’, a NIST resource [18] containing mostly experimental and averaged values

‘JOBACK’, an estimation method for organic substances in [19]

‘PINAMARTINES’, a series of values in the supporting material of [20]

‘WILSON_JASPERSON’, an estimation method in [21]

‘HEOS’, a series of values from the NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids (and other high-precision fundamental equations of state)

References

1: Ambrose, Douglas, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 1. An Introductory Survey.” Journal of Chemical & Engineering Data 41, no. 1 (January 1, 1996): 154-154. doi:10.1021/je950378q.
2: Ambrose, Douglas, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 2. Normal Alkanes.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 531-46. doi:10.1021/je00019a001.
3: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 3. Aromatic Hydrocarbons.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 547-58. doi:10.1021/je00019a002.
4: Gude, Michael, and Amyn S. Teja. “Vapor-Liquid Critical Properties of Elements and Compounds. 4. Aliphatic Alkanols.” Journal of Chemical & Engineering Data 40, no. 5 (September 1, 1995): 1025-36. doi:10.1021/je00021a001.
5: Daubert, Thomas E. “Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes.” Journal of Chemical & Engineering Data 41, no. 3 (January 1, 1996): 365-72. doi:10.1021/je9501548.
6: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons.” Journal of Chemical & Engineering Data 41, no. 4 (January 1, 1996): 645-56. doi:10.1021/je9501999.
7: Kudchadker, Arvind P., Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 7. Oxygen Compounds Other Than Alkanols and Cycloalkanols.” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 457-79. doi:10.1021/je0001680.
8: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 8. Organic Sulfur, Silicon, and Tin Compounds (C + H + S, Si, and Sn).” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 480-85. doi:10.1021/je000210r.
9: Marsh, Kenneth N., Colin L. Young, David W. Morton, Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 9. Organic Compounds Containing Nitrogen.” Journal of Chemical & Engineering Data 51, no. 2 (March 1, 2006): 305-14. doi:10.1021/je050221q.
10: Marsh, Kenneth N., Alan Abramson, Douglas Ambrose, David W. Morton, Eugene Nikitin, Constantine Tsonopoulos, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 10. Organic Compounds Containing Halogens.” Journal of Chemical & Engineering Data 52, no. 5 (September 1, 2007): 1509-38. doi:10.1021/je700336g.
11: Ambrose, Douglas, Constantine Tsonopoulos, and Eugene D. Nikitin. “Vapor-Liquid Critical Properties of Elements and Compounds. 11. Organic Compounds Containing B + O; Halogens + N, + O, + O + S, + S, + Si; N + O; and O + S, + Si.” Journal of Chemical & Engineering Data 54, no. 3 (March 12, 2009): 669-89. doi:10.1021/je800580z.
12: Ambrose, Douglas, Constantine Tsonopoulos, Eugene D. Nikitin, David W. Morton, and Kenneth N. Marsh. “Vapor-Liquid Critical Properties of Elements and Compounds. 12. Review of Recent Data for Hydrocarbons and Non-Hydrocarbons.” Journal of Chemical & Engineering Data, October 5, 2015, 151005081500002. doi:10.1021/acs.jced.5b00571.
13: Mathews, Joseph F. “Critical Constants of Inorganic Substances.” Chemical Reviews 72, no. 1 (February 1, 1972): 71-100. doi:10.1021/cr60275a004.
14: Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
15: Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and Jürgen Gmehling. “PSRK Group Contribution Equation of State: Comprehensive Revision and Extension IV, Including Critical Constants and A-Function Parameters for 1000 Components.” Fluid Phase Equilibria 227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
16: Passut, Charles A., and Ronald P. Danner. “Acentric Factor. A Valuable Correlating Parameter for the Properties of Hydrocarbons.” Industrial & Engineering Chemistry Process Design and Development 12, no. 3 (July 1, 1973): 365-68. doi:10.1021/i260047a026.
17: Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.
18: Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
19: Joback, K.G., and R.C. Reid. “Estimation of Pure-Component Properties from Group-Contributions.” Chemical Engineering Communications 57, no. 1-6 (July 1, 1987): 233-43. doi:10.1080/00986448708960487.
20: Piña-Martinez, Andrés, Romain Privat, and Jean-Noël Jaubert. “Use of 300,000 Pseudo-Experimental Data over 1800 Pure Fluids to Assess the Performance of Four Cubic Equations of State: SRK, PR, Tc-RK, and Tc-PR.” AIChE Journal n/a, no. n/a (n.d.): e17518. https://doi.org/10.1002/aic.17518.
21: Wilson, G. M., and L. V. Jasperson. “Critical Constants Tc, Pc, Estimation Based on Zero, First and Second Order Methods.” In Proceedings of the AIChE Spring Meeting, 21, 1996.
22: Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.

Examples

>>> Pc(CASRN='64-17-5')
6268000.0

chemicals.critical.Pc_methods(CASRN)[source]¶

Return all methods available to obtain the critical pressure for the desired chemical.

Parameters

CASRNstr: CASRN, [-]

Returns

methodslist[str]: Methods which can be used to obtain Pc with the given inputs.

See also

Pc

chemicals.critical.Pc_all_methods = ('HEOS', 'IUPAC', 'MATTHEWS', 'CRC', 'PD', 'WEBBOOK', 'PSRK', 'PINAMARTINES', 'YAWS', 'WILSON_JASPERSON', 'JOBACK')¶: Tuple of method name keys. See the Pc for the actual references

Critical Volume ¶

chemicals.critical.Vc(CASRN, method=None)[source]¶

This function handles the retrieval of a chemical’s critical volume. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Preferred sources are ‘IUPAC’ for organic chemicals, and ‘MATTHEWS’ for inorganic chemicals. Function has data for approximately 25000 chemicals.

Parameters

CASRNstr: CASRN [-]

Returns

Vcfloat: Critical volume, [m^3/mol]

Other Parameters

methodstr, optional: The method name to use. Accepted methods are ‘IUPAC’, ‘MATTHEWS’, ‘CRC’, ‘WEBBOOK’, ‘PSRK’, ‘PINAMARTINES’, ‘YAWS’, ‘FEDORS’, ‘JOBACK’, ‘HEOS’. All valid values are also held in the list Vc_all_methods.

See also

Vc_methods

Notes

The available sources are as follows:

‘IUPAC’, a series of critically evaluated experimental datum for organic compounds in [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], and [12].

‘MATTHEWS’, a series of critically evaluated data for inorganic compounds in [13].

‘CRC’, a compillation of critically evaluated data by the TRC as published in [14].

‘PSRK’, a compillation of experimental and estimated data published in [15].

‘YAWS’, a large compillation of data from a variety of sources; no data points are sourced in the work of [16].

‘WEBBOOK’, a NIST resource [17] containing mostly experimental and averaged values

‘JOBACK’, an estimation method for organic substances in [18]

‘FEDORS’, an estimation methid in [20]

‘PINAMARTINES’, a series of values in the supporting material of [19]

‘HEOS’, a series of values from the NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids (and other high-precision fundamental equations of state)

References

1: Ambrose, Douglas, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 1. An Introductory Survey.” Journal of Chemical & Engineering Data 41, no. 1 (January 1, 1996): 154-154. doi:10.1021/je950378q.
2: Ambrose, Douglas, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 2. Normal Alkanes.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 531-46. doi:10.1021/je00019a001.
3: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 3. Aromatic Hydrocarbons.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 547-58. doi:10.1021/je00019a002.
4: Gude, Michael, and Amyn S. Teja. “Vapor-Liquid Critical Properties of Elements and Compounds. 4. Aliphatic Alkanols.” Journal of Chemical & Engineering Data 40, no. 5 (September 1, 1995): 1025-36. doi:10.1021/je00021a001.
5: Daubert, Thomas E. “Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes.” Journal of Chemical & Engineering Data 41, no. 3 (January 1, 1996): 365-72. doi:10.1021/je9501548.
6: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons.” Journal of Chemical & Engineering Data 41, no. 4 (January 1, 1996): 645-56. doi:10.1021/je9501999.
7: Kudchadker, Arvind P., Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 7. Oxygen Compounds Other Than Alkanols and Cycloalkanols.” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 457-79. doi:10.1021/je0001680.
8: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 8. Organic Sulfur, Silicon, and Tin Compounds (C + H + S, Si, and Sn).” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 480-85. doi:10.1021/je000210r.
9: Marsh, Kenneth N., Colin L. Young, David W. Morton, Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 9. Organic Compounds Containing Nitrogen.” Journal of Chemical & Engineering Data 51, no. 2 (March 1, 2006): 305-14. doi:10.1021/je050221q.
10: Marsh, Kenneth N., Alan Abramson, Douglas Ambrose, David W. Morton, Eugene Nikitin, Constantine Tsonopoulos, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 10. Organic Compounds Containing Halogens.” Journal of Chemical & Engineering Data 52, no. 5 (September 1, 2007): 1509-38. doi:10.1021/je700336g.
11: Ambrose, Douglas, Constantine Tsonopoulos, and Eugene D. Nikitin. “Vapor-Liquid Critical Properties of Elements and Compounds. 11. Organic Compounds Containing B + O; Halogens + N, + O, + O + S, + S, + Si; N + O; and O + S, + Si.” Journal of Chemical & Engineering Data 54, no. 3 (March 12, 2009): 669-89. doi:10.1021/je800580z.
12: Ambrose, Douglas, Constantine Tsonopoulos, Eugene D. Nikitin, David W. Morton, and Kenneth N. Marsh. “Vapor-Liquid Critical Properties of Elements and Compounds. 12. Review of Recent Data for Hydrocarbons and Non-Hydrocarbons.” Journal of Chemical & Engineering Data, October 5, 2015, 151005081500002. doi:10.1021/acs.jced.5b00571.
13: Mathews, Joseph F. “Critical Constants of Inorganic Substances.” Chemical Reviews 72, no. 1 (February 1, 1972): 71-100. doi:10.1021/cr60275a004.
14: Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
15: Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and Jürgen Gmehling. “PSRK Group Contribution Equation of State: Comprehensive Revision and Extension IV, Including Critical Constants and A-Function Parameters for 1000 Components.” Fluid Phase Equilibria 227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
16: Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.
17: Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
18: Joback, K.G., and R.C. Reid. “Estimation of Pure-Component Properties from Group-Contributions.” Chemical Engineering Communications 57, no. 1-6 (July 1, 1987): 233-43. doi:10.1080/00986448708960487.
19: Piña-Martinez, Andrés, Romain Privat, and Jean-Noël Jaubert. “Use of 300,000 Pseudo-Experimental Data over 1800 Pure Fluids to Assess the Performance of Four Cubic Equations of State: SRK, PR, Tc-RK, and Tc-PR.” AIChE Journal n/a, no. n/a (n.d.): e17518. https://doi.org/10.1002/aic.17518.
20: Fedors, R. F. “A Method to Estimate Critical Volumes.” AIChE Journal 25, no. 1 (1979): 202-202. https://doi.org/10.1002/aic.690250129.
21: Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.

Examples

>>> Vc(CASRN='64-17-5')
0.000168634064081

chemicals.critical.Vc_methods(CASRN)[source]¶

Return all methods available to obtain the critical volume for the desired chemical.

Parameters

CASRNstr: CASRN, [-]

Returns

methodslist[str]: Methods which can be used to obtain Vc with the given inputs.

See also

Vc

chemicals.critical.Vc_all_methods = ('HEOS', 'IUPAC', 'MATTHEWS', 'CRC', 'WEBBOOK', 'PSRK', 'PINAMARTINES', 'YAWS', 'FEDORS', 'JOBACK')¶: Tuple of method name keys. See the Vc for the actual references

chemicals.critical.Mersmann_Kind_predictor(atoms, coeff=3.645, power=0.5, covalent_radii={'Br': 1.14, 'C': 0.77, 'Cl': 0.99, 'F': 0.71, 'H': 0.37, 'I': 1.33, 'N': 0.71, 'O': 0.6, 'S': 1.04, 'Si': 1.17})[source]¶

Predicts the critical molar volume of a chemical based only on its atomic composition according to [1] and [2]. This is a crude approach, but provides very reasonable estimates in practice. Optionally, the coeff used and the power in the fraction as well as the atomic contributions can be adjusted; this method is general and atomic contributions can be regressed to predict other properties with this routine.

\frac{\left(\frac{V_c}{n_a N_A}\right)^{1/3}}{d_a} = \frac{3.645}{\left(\frac{r_a}{r_H}\right)^{1/2}} r_a = d_a/2 d_a = 2 \frac{\sum_i (n_i r_i)}{n_a}

In the above equations, $n_i$ is the number of atoms of species i in the molecule, $r_i$ is the covalent atomic radius of the atom, and $n_a$ is the total number of atoms in the molecule.

Parameters

atomsdict: Dictionary of atoms and their counts, [-]
coefffloat, optional: Coefficient used in the relationship, [m^2]
powerfloat, optional: Power applied to the relative atomic radius, [-]
covalent_radiidict or indexable, optional: Object which can be indexed to atomic contrinbutions (by symbol), [-]

Returns

Vcfloat: Predicted critical volume of the chemical, [m^3/mol]

Notes

Using the chemicals.elements.periodic_table covalent radii (from RDKit), the coefficient and power should be 4.261206523632586 and 0.5597281770786228 respectively for best results.

References

1: Mersmann, Alfons, and Matthias Kind. “Correlation for the Prediction of Critical Molar Volume.” Industrial & Engineering Chemistry Research, October 16, 2017. https://doi.org/10.1021/acs.iecr.7b03171.
2: Mersmann, Alfons, and Matthias Kind. “Prediction of Mechanical and Thermal Properties of Pure Liquids, of Critical Data, and of Vapor Pressure.” Industrial & Engineering Chemistry Research, January 31, 2017. https://doi.org/10.1021/acs.iecr.6b04323.

Examples

Prediction of critical volume of decane:

>>> Mersmann_Kind_predictor({'C': 10, 'H': 22})
0.0005851858957767497

This is compared against the experimental value, 0.000624 (a 6.2% relative error)

Using custom fitted coefficients we can do a bit better:

>>> from chemicals.critical import rcovs_regressed
>>> Mersmann_Kind_predictor({'C': 10, 'H': 22}, coeff=4.261206523632586,
... power=0.5597281770786228, covalent_radii=rcovs_regressed)
0.0005956870915974391

The relative error is only 4.5% now. This is compared to an experimental uncertainty of 5.6%.

Evaluating 1321 critical volumes in the database, the average relative error is 5.0%; standard deviation 6.8%; and worst value of 79% relative error for phosphorus.

Critical Compressibility Factor ¶

chemicals.critical.Zc(CASRN, method=None)[source]¶

This function handles the retrieval of a chemical’s critical compressibility. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Preferred sources are ‘IUPAC’ for organic chemicals, and ‘MATTHEWS’ for inorganic chemicals. Function has data for approximately 25000 chemicals.

Parameters

CASRNstr: CASRN [-]

Returns

Zcfloat: Critical compressibility, [-]

Other Parameters

methodstr, optional: The method name to use. Accepted methods are ‘IUPAC’, ‘MATTHEWS’, ‘CRC’, ‘PSRK’, ‘YAWS’, ‘HEOS’. All valid values are also held in Zc_all_methods.

See also

Zc_methods

Notes

The available sources are as follows:

‘IUPAC’, a series of critically evaluated experimental datum for organic compounds in [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], and [12].

‘MATTHEWS’, a series of critically evaluated data for inorganic compounds in [13].

‘CRC’, a compillation of critically evaluated data by the TRC as published in [14].

‘PSRK’, a compillation of experimental and estimated data published in [15].

‘YAWS’, a large compillation of data from a variety of sources; no data points are sourced in the work of [16].

‘WEBBOOK’, a NIST resource [17] containing mostly experimental and averaged values

‘JOBACK’, an estimation method for organic substances in [18]

‘PINAMARTINES’, a series of values in the supporting material of [19]

‘HEOS’, a series of values from the NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids (and other high-precision fundamental equations of state)

References

1: Ambrose, Douglas, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 1. An Introductory Survey.” Journal of Chemical & Engineering Data 41, no. 1 (January 1, 1996): 154-154. doi:10.1021/je950378q.
2: Ambrose, Douglas, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 2. Normal Alkanes.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 531-46. doi:10.1021/je00019a001.
3: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 3. Aromatic Hydrocarbons.” Journal of Chemical & Engineering Data 40, no. 3 (May 1, 1995): 547-58. doi:10.1021/je00019a002.
4: Gude, Michael, and Amyn S. Teja. “Vapor-Liquid Critical Properties of Elements and Compounds. 4. Aliphatic Alkanols.” Journal of Chemical & Engineering Data 40, no. 5 (September 1, 1995): 1025-36. doi:10.1021/je00021a001.
5: Daubert, Thomas E. “Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes.” Journal of Chemical & Engineering Data 41, no. 3 (January 1, 1996): 365-72. doi:10.1021/je9501548.
6: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons.” Journal of Chemical & Engineering Data 41, no. 4 (January 1, 1996): 645-56. doi:10.1021/je9501999.
7: Kudchadker, Arvind P., Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 7. Oxygen Compounds Other Than Alkanols and Cycloalkanols.” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 457-79. doi:10.1021/je0001680.
8: Tsonopoulos, Constantine, and Douglas Ambrose. “Vapor-Liquid Critical Properties of Elements and Compounds. 8. Organic Sulfur, Silicon, and Tin Compounds (C + H + S, Si, and Sn).” Journal of Chemical & Engineering Data 46, no. 3 (May 1, 2001): 480-85. doi:10.1021/je000210r.
9: Marsh, Kenneth N., Colin L. Young, David W. Morton, Douglas Ambrose, and Constantine Tsonopoulos. “Vapor-Liquid Critical Properties of Elements and Compounds. 9. Organic Compounds Containing Nitrogen.” Journal of Chemical & Engineering Data 51, no. 2 (March 1, 2006): 305-14. doi:10.1021/je050221q.
10: Marsh, Kenneth N., Alan Abramson, Douglas Ambrose, David W. Morton, Eugene Nikitin, Constantine Tsonopoulos, and Colin L. Young. “Vapor-Liquid Critical Properties of Elements and Compounds. 10. Organic Compounds Containing Halogens.” Journal of Chemical & Engineering Data 52, no. 5 (September 1, 2007): 1509-38. doi:10.1021/je700336g.
11: Ambrose, Douglas, Constantine Tsonopoulos, and Eugene D. Nikitin. “Vapor-Liquid Critical Properties of Elements and Compounds. 11. Organic Compounds Containing B + O; Halogens + N, + O, + O + S, + S, + Si; N + O; and O + S, + Si.” Journal of Chemical & Engineering Data 54, no. 3 (March 12, 2009): 669-89. doi:10.1021/je800580z.
12: Ambrose, Douglas, Constantine Tsonopoulos, Eugene D. Nikitin, David W. Morton, and Kenneth N. Marsh. “Vapor-Liquid Critical Properties of Elements and Compounds. 12. Review of Recent Data for Hydrocarbons and Non-Hydrocarbons.” Journal of Chemical & Engineering Data, October 5, 2015, 151005081500002. doi:10.1021/acs.jced.5b00571.
13: Mathews, Joseph F. “Critical Constants of Inorganic Substances.” Chemical Reviews 72, no. 1 (February 1, 1972): 71-100. doi:10.1021/cr60275a004.
14: Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
15: Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and Jürgen Gmehling. “PSRK Group Contribution Equation of State: Comprehensive Revision and Extension IV, Including Critical Constants and A-Function Parameters for 1000 Components.” Fluid Phase Equilibria 227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
16: Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.
17: Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
18: Joback, K.G., and R.C. Reid. “Estimation of Pure-Component Properties from Group-Contributions.” Chemical Engineering Communications 57, no. 1-6 (July 1, 1987): 233-43. doi:10.1080/00986448708960487.
19: Piña-Martinez, Andrés, Romain Privat, and Jean-Noël Jaubert. “Use of 300,000 Pseudo-Experimental Data over 1800 Pure Fluids to Assess the Performance of Four Cubic Equations of State: SRK, PR, Tc-RK, and Tc-PR.” AIChE Journal n/a, no. n/a (n.d.): e17518. https://doi.org/10.1002/aic.17518.
20: Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.

Examples

>>> Zc(CASRN='64-17-5')
0.247

chemicals.critical.Zc_methods(CASRN)[source]¶

Return all methods available to obtain the critical compressibility for the desired chemical.

Parameters

CASRNstr: CASRN, [-]

Returns

methodslist[str]: Methods which can be used to obtain Zc with the given inputs.

See also

Zc

chemicals.critical.Zc_all_methods = ('HEOS', 'IUPAC', 'MATTHEWS', 'CRC', 'WEBBOOK', 'PSRK', 'PINAMARTINES', 'YAWS', 'JOBACK')¶: Tuple of method name keys. See the Zc for the actual references

Critical Property Relationships ¶

chemicals.critical.critical_surface(Tc=None, Pc=None, Vc=None, method=None)[source]¶

Function for calculating a critical property of a substance from its other two critical properties. Calls functions Ihmels, Meissner, and Grigoras, each of which use a general ‘Critical surface’ type of equation. Limited accuracy is expected due to very limited theoretical backing.

Parameters

Tcfloat: Critical temperature of fluid (optional) [K].
Pcfloat: Critical pressure of fluid (optional) [Pa].
Vcfloat: Critical volume of fluid (optional) [m^3/mol].
methodstr: Request calculation uses the requested method.

Returns

Tc, Pc or Vcfloat: Critical property of fluid [K], [Pa], or [m^3/mol].

See also

critical_surface_methods_methods

Examples

Decamethyltetrasiloxane [141-62-8]

>>> critical_surface(Tc=599.4, Pc=1.19E6, method='IHMELS')
0.0010927333333333334

chemicals.critical.critical_surface_methods(Tc=None, Pc=None, Vc=None)[source]¶

Return all methods available to obtain the third critial property for the desired chemical.

Parameters

Tcfloat: Critical temperature of fluid (optional) [K].
Pcfloat: Critical pressure of fluid (optional) [Pa].
Vcfloat: Critical volume of fluid (optional) [m^3/mol].

Returns

methodslist[str]: Methods which can be used to obtain the third critical property with the given inputs.

See also

critical_surface

chemicals.critical.critical_surface_all_methods = ('IHMELS', 'MEISSNER', 'GRIGORAS')¶

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable’s items.

If the argument is a tuple, the return value is the same object.

chemicals.critical.third_property(CASRN=None, T=False, P=False, V=False)[source]¶

Function for calculating a critical property of a substance from its other two critical properties, but retrieving the actual other critical values for convenient calculation. Calls functions Ihmels, Meissner, and Grigoras, each of which use a general ‘Critical surface’ type of equation. Limited accuracy is expected due to very limited theoretical backing.

Parameters

CASRNstr: The CAS number of the desired chemical
Tbool: Estimate critical temperature
Pbool: Estimate critical pressure
Vbool: Estimate critical volume

Returns

Tc, Pc or Vcfloat: Critical property of fluid [K], [Pa], or [m^3/mol]

Examples

Decamethyltetrasiloxane [141-62-8]

>>> third_property('141-62-8', V=True)
0.001135732

Succinic acid [110-15-6]

>>> third_property('110-15-6', P=True)
6095016.233766234

chemicals.critical.Ihmels(Tc=None, Pc=None, Vc=None)[source]¶

Most recent, and most recommended method of estimating critical properties from each other. Two of the three properties are required. This model uses the “critical surface”, a general plot of Tc vs Pc vs Vc. The model used 421 organic compounds to derive equation. The general equation is in [1]:

P_c = -0.025 + 2.215 \frac{T_c}{V_c}

Parameters

Tcfloat: Critical temperature of fluid (optional) [K]
Pcfloat: Critical pressure of fluid (optional) [Pa]
Vcfloat: Critical volume of fluid (optional) [m^3/mol]

Returns

Tc, Pc or Vcfloat: Critical property of fluid [K], [Pa], or [m^3/mol]

Notes

The prediction of Tc from Pc and Vc is not tested, as this is not necessary anywhere, but it is implemented. Internal units are MPa, cm^3/mol, and K. A slight error occurs when Pa, cm^3/mol and K are used instead, on the order of <0.2%. Their equation was also compared with 56 inorganic and elements. Devations of 20% for <200K or >1000K points.

References

1: Ihmels, E. Christian. “The Critical Surface.” Journal of Chemical & Engineering Data 55, no. 9 (September 9, 2010): 3474-80. doi:10.1021/je100167w.

Examples

Succinic acid [110-15-6]

>>> Ihmels(Tc=851.0, Vc=0.000308)
6095016.233766234

chemicals.critical.Meissner(Tc=None, Pc=None, Vc=None)[source]¶

Old (1942) relationship for estimating critical properties from each other. Two of the three properties are required. This model uses the “critical surface”, a general plot of Tc vs Pc vs Vc. The model used 42 organic and inorganic compounds to derive the equation. The general equation is in [1]:

P_c = \frac{2.08 T_c}{V_c-8}

Parameters

Tcfloat, optional: Critical temperature of fluid [K]
Pcfloat, optional: Critical pressure of fluid [Pa]
Vcfloat, optional: Critical volume of fluid [m^3/mol]

Returns

Tc, Pc or Vcfloat: Critical property of fluid [K], [Pa], or [m^3/mol]

Notes

The prediction of Tc from Pc and Vc is not tested, as this is not necessary anywhere, but it is implemented. Internal units are atm, cm^3/mol, and K. A slight error occurs when Pa, cm^3/mol and K are used instead, on the order of <0.2%. This equation is less accurate than that of Ihmels, but surprisingly close. The author also proposed means of estimated properties independently.

References

1: Meissner, H. P., and E. M. Redding. “Prediction of Critical Constants.” Industrial & Engineering Chemistry 34, no. 5 (May 1, 1942): 521-26. doi:10.1021/ie50389a003.

Examples

Succinic acid [110-15-6]

>>> Meissner(Tc=851.0, Vc=0.000308)
5978445.199999999

chemicals.critical.Grigoras(Tc=None, Pc=None, Vc=None)[source]¶

Relatively recent (1990) relationship for estimating critical properties from each other. Two of the three properties are required. This model uses the “critical surface”, a general plot of Tc vs Pc vs Vc. The model used 137 organic and inorganic compounds to derive the equation. The general equation is in [1]:

P_c = 2.9 + 20.2 \frac{T_c}{V_c}

Parameters

Tcfloat, optional: Critical temperature of fluid [K]
Pcfloat, optional: Critical pressure of fluid [Pa]
Vcfloat, optional: Critical volume of fluid [m^3/mol]

Returns

Tc, Pc or Vcfloat: Critical property of fluid [K], [Pa], or [m^3/mol]

Notes

The prediction of Tc from Pc and Vc is not tested, as this is not necessary anywhere, but it is implemented. Internal units are bar, cm^3/mol, and K. A slight error occurs when Pa, cm^3/mol and K are used instead, on the order of <0.2%. This equation is less accurate than that of Ihmels, but surprisingly close. The author also investigated an early QSPR model.

References

1: Grigoras, Stelian. “A Structural Approach to Calculate Physical Properties of Pure Organic Substances: The Critical Temperature, Critical Volume and Related Properties.” Journal of Computational Chemistry 11, no. 4 (May 1, 1990): 493-510. doi:10.1002/jcc.540110408

Examples

Succinic acid [110-15-6]

>>> Grigoras(Tc=851.0, Vc=0.000308)
5871233.766233766

chemicals.critical.Hekayati_Raeissi(MW, V_sat=None, Tc=None, Pc=None, Vc=None)[source]¶

Estimation model for missing critical constants of a fluid according to [1]. Based on the molecular weight and saturation molar volume of a fluid, and requires one of Tc or Pc. Optionally, Vc can be provided to increase the accuracy of the prediction of Tc or Pc a little.

Parameters

MWfloat: Molecular weight of fluid, [g/mol]
V_satfloat, optional: Molar volume of liquid at the saturation pressure of the fluid at 298.15 K. Used if Vc is not provided. [m^3/mol]
Tcfloat, optional: Critical temperature of fluid (optional) [K]
Pcfloat, optional: Critical pressure of fluid (optional) [Pa]
Vcfloat, optional: Critical volume of fluid (optional) [m^3/mol]

Returns

Tcfloat: Critical temperature of fluid [K]
Pcfloat: Critical pressure of fluid [Pa]
Vcfloat: Critical volume of fluid [m^3/mol]

Notes

Internal units are kPa, m^3/kmol, and K.

References

1: Hekayati, Javad, and Sona Raeissi. “Estimation of the Critical Properties of Compounds Using Volume-Based Thermodynamics.” AIChE Journal n/a, no. n/a (n.d.): e17004. https://doi.org/10.1002/aic.17004.

Examples

Toluene

>>> Hekayati_Raeissi(MW=92.13842, V_sat=0.00010686, Pc=4108000.0)
(599.7965819136947, 4108000.0, 0.000314909150453723)

chemicals.critical.Tb_Tc_relationship(Tb=None, Tc=None, fit='Perry8E')[source]¶

This function relates the normal boiling point and the critical point of a compound. It is inspired by the relationship shown in [1] on page 2-468 for inorganic compounds.

T_c = 1.64 T_b

Parameters

Tbfloat, optional: Normal boiling temperature of fluid [K]
Tcfloat, optional: Critical temperature of fluid [K]
fitstr, optional: One of ‘Perry8E’, ‘Chemicals2021FitInorganic’, ‘Chemicals2021FitElements’, ‘Chemicals2021FitBinary’, ‘Chemicals2021FitTernary’, Chemicals2021FitOrganic’, ‘Chemicals2021FitBr’, ‘Chemicals2021FitC’, ‘Chemicals2021FitCl’, ‘Chemicals2021FitF’, ‘Chemicals2021FitI’, ‘Chemicals2021FitN’, ‘Chemicals2021FitO’, ‘ ‘Chemicals2021FitSi’.

Returns

Tc or Tbfloat: The temperature variable not provided [K]

Notes

Chemicals2021FitBinary applies for inorganic compounds with two types of atoms; Chemicals2021FitTernary for three; and the various models Chemicals2021FitO, Chemicals2021FitC, etc apply for inorganic compounds with those elements in them.

The quality of this relationship is low, but if no further information is available it can be used to obtain an approximate value.

References

1: Green, Don, and Robert Perry. Perry’s Chemical Engineers’ Handbook, Eighth Edition. McGraw-Hill Professional, 2007.

Examples

Tetrabromosilane has a known boiling point of 427.15 K and a critical temperature of 663.0 K.

>>> Tb_Tc_relationship(Tb=427.15, fit='Perry8E')
700.526
>>> Tb_Tc_relationship(Tb=427.15, fit='Chemicals2021FitBr')
668.0626
>>> Tb_Tc_relationship(Tb=427.15, fit='Chemicals2021FitSi')
651.8309
>>> Tb_Tc_relationship(Tb=427.15, fit='Chemicals2021FitBinary')
669.7712
>>> Tb_Tc_relationship(Tb=427.15, fit='Chemicals2021FitInorganic')
686.0029

The performance of the fits is fairly representative. However, because this method should only be used on compounds that don’t have experimental critical points measured, many of the worst outlier chemicals have already been measured and the performance may be better than expected.

It is recommended to use the methods Chemicals2021FitElements, Chemicals2021FitBinary, and Chemicals2021FitTernary.

Critical Temperature of Mixtures ¶

chemicals.critical.Li(zs, Tcs, Vcs)[source]¶

Calculates critical temperature of a mixture according to mixing rules in [1]. Better than simple mixing rules.

T_{cm} = \sum_{i=1}^n \Phi_i T_{ci}\\ \Phi = \frac{x_i V_{ci}}{\sum_{j=1}^n x_j V_{cj}}

Parameters

zsarray_like: Mole fractions of all components
Tcsarray_like: Critical temperatures of all components, [K]
Vcsarray_like: Critical volumes of all components, [m^3/mol]

Returns

Tcmfloat: Critical temperatures of the mixture, [K]

Notes

Reviewed in many papers on critical mixture temperature.

Second example is from Najafi (2015), for ethylene, Benzene, ethylbenzene. This is similar to but not identical to the result from the article. The experimental point is 486.9 K.

2rd example is from Najafi (2015), for: butane/pentane/hexane 0.6449/0.2359/0.1192 mixture, exp: 450.22 K. Its result is identical to that calculated in the article.

References

1: Li, C. C. “Critical Temperature Estimation for Simple Mixtures.” The Canadian Journal of Chemical Engineering 49, no. 5 (October 1, 1971): 709-10. doi:10.1002/cjce.5450490529.

Examples

Nitrogen-Argon 50/50 mixture

>>> Li([0.5, 0.5], [126.2, 150.8], [8.95e-05, 7.49e-05])
137.40766423357667

butane/pentane/hexane 0.6449/0.2359/0.1192 mixture, exp: 450.22 K.

>>> Li([0.6449, 0.2359, 0.1192], [425.12, 469.7, 507.6],
... [0.000255, 0.000313, 0.000371])
449.68261498555444

chemicals.critical.Chueh_Prausnitz_Tc(zs, Tcs, Vcs, taus)[source]¶

Calculates critical temperature of a mixture according to mixing rules in [1].

T_{cm} = \sum_i^n \theta_i Tc_i + \sum_i^n\sum_j^n(\theta_i \theta_j \tau_{ij})T_{ref} \theta = \frac{x_i V_{ci}^{2/3}}{\sum_{j=1}^n x_j V_{cj}^{2/3}}

For a binary mxiture, this simplifies to:

T_{cm} = \theta_1T_{c1} + \theta_2T_{c2} + 2\theta_1\theta_2\tau_{12}

Parameters

zsarray_like: Mole fractions of all components
Tcsarray_like: Critical temperatures of all components, [K]
Vcsarray_like: Critical volumes of all components, [m^3/mol]
tausarray_like of shape zs by zs: Interaction parameters, [-]

Returns

Tcmfloat: Critical temperatures of the mixture, [K]

Notes

All parameters, even if zero, must be given to this function.

References

1: Chueh, P. L., and J. M. Prausnitz. “Vapor-Liquid Equilibria at High Pressures: Calculation of Critical Temperatures, Volumes, and Pressures of Nonpolar Mixtures.” AIChE Journal 13, no. 6 (November 1, 1967): 1107-13. doi:10.1002/aic.690130613.
2: Najafi, Hamidreza, Babak Maghbooli, and Mohammad Amin Sobati. “Prediction of True Critical Temperature of Multi-Component Mixtures: Extending Fast Estimation Methods.” Fluid Phase Equilibria 392 (April 25, 2015): 104-26. doi:10.1016/j.fluid.2015.02.001.

Examples

butane/pentane/hexane 0.6449/0.2359/0.1192 mixture, exp: 450.22 K.

>>> Chueh_Prausnitz_Tc([0.6449, 0.2359, 0.1192], [425.12, 469.7, 507.6],
... [0.000255, 0.000313, 0.000371], [[0, 1.92681, 6.80358],
... [1.92681, 0, 1.89312], [ 6.80358, 1.89312, 0]])
450.122576472349

chemicals.critical.Grieves_Thodos(zs, Tcs, Aijs)[source]¶

Calculates critical temperature of a mixture according to mixing rules in [1].

T_{cm} = \sum_{i} \frac{T_{ci}}{1 + (1/x_i)\sum_j A_{ij} x_j}

For a binary mxiture, this simplifies to:

T_{cm} = \frac{T_{c1}}{1 + (x_2/x_1)A_{12}} + \frac{T_{c2}} {1 + (x_1/x_2)A_{21}}

Parameters

zsarray_like: Mole fractions of all components
Tcsarray_like: Critical temperatures of all components, [K]
Aijsarray_like of shape zs by zs: Interaction parameters

Returns

Tcmfloat: Critical temperatures of the mixture, [K]

Notes

All parameters, even if zero, must be given to this function. Giving 0s gives really bad results however.

References

1: Grieves, Robert B., and George Thodos. “The Critical Temperatures of Multicomponent Hydrocarbon Systems.” AIChE Journal 8, no. 4 (September 1, 1962): 550-53. doi:10.1002/aic.690080426.
2: Najafi, Hamidreza, Babak Maghbooli, and Mohammad Amin Sobati. “Prediction of True Critical Temperature of Multi-Component Mixtures: Extending Fast Estimation Methods.” Fluid Phase Equilibria 392 (April 25, 2015): 104-26. doi:10.1016/j.fluid.2015.02.001.

Examples

butane/pentane/hexane 0.6449/0.2359/0.1192 mixture, exp: 450.22 K.

>>> Grieves_Thodos([0.6449, 0.2359, 0.1192], [425.12, 469.7, 507.6], [[0, 1.2503, 1.516], [0.799807, 0, 1.23843], [0.659633, 0.807474, 0]])
450.1839618758971

chemicals.critical.modified_Wilson_Tc(zs, Tcs, Aijs)[source]¶

Calculates critical temperature of a mixture according to mixing rules in [1]. Equation

T_{cm} = \sum_i x_i T_{ci} + C\sum_i x_i \ln \left(x_i + \sum_j x_j A_{ij}\right)T_{ref}

For a binary mxiture, this simplifies to:

T_{cm} = x_1 T_{c1} + x_2 T_{c2} + C[x_1 \ln(x_1 + x_2A_{12}) + x_2\ln(x_2 + x_1 A_{21})]

Parameters

zsfloat: Mole fractions of all components
Tcsfloat: Critical temperatures of all components, [K]
Aijsmatrix: Interaction parameters

Returns

Tcmfloat: Critical temperatures of the mixture, [K]

Notes

The equation and original article has been reviewed. [1] has 75 binary systems, and additional multicomponent mixture parameters. All parameters, even if zero, must be given to this function.

2rd example is from [2], for: butane/pentane/hexane 0.6449/0.2359/0.1192 mixture, exp: 450.22 K. Its result is identical to that calculated in the article.

References

1(1,2): Teja, Amyn S., Kul B. Garg, and Richard L. Smith. “A Method for the Calculation of Gas-Liquid Critical Temperatures and Pressures of Multicomponent Mixtures.” Industrial & Engineering Chemistry Process Design and Development 22, no. 4 (1983): 672-76.
2: Najafi, Hamidreza, Babak Maghbooli, and Mohammad Amin Sobati. “Prediction of True Critical Temperature of Multi-Component Mixtures: Extending Fast Estimation Methods.” Fluid Phase Equilibria 392 (April 25, 2015): 104-26. doi:10.1016/j.fluid.2015.02.001.

Examples

>>> modified_Wilson_Tc([0.6449, 0.2359, 0.1192], [425.12, 469.7, 507.6],
... [[0, 1.174450, 1.274390], [0.835914, 0, 1.21038],
... [0.746878, 0.80677, 0]])
450.03059668230316

Critical Volume of Mixtures ¶

chemicals.critical.Chueh_Prausnitz_Vc(zs, Vcs, nus)[source]¶

Calculates critical volume of a mixture according to mixing rules in [1] with an interaction parameter.

V_{cm} = \sum_i^n \theta_i V_{ci} + \sum_i^n\sum_j^n(\theta_i \theta_j \nu_{ij})V_{ref} \theta = \frac{x_i V_{ci}^{2/3}}{\sum_{j=1}^n x_j V_{cj}^{2/3}}

Parameters

zsfloat: Mole fractions of all components
Vcsfloat: Critical volumes of all components, [m^3/mol]
nusmatrix: Interaction parameters, [cm^3/mol]

Returns

Vcmfloat: Critical volume of the mixture, [m^3/mol]

Notes

All parameters, even if zero, must be given to this function. nu parameters are in cm^3/mol, but are converted to m^3/mol inside the function

References

1: Chueh, P. L., and J. M. Prausnitz. “Vapor-Liquid Equilibria at High Pressures: Calculation of Critical Temperatures, Volumes, and Pressures of Nonpolar Mixtures.” AIChE Journal 13, no. 6 (November 1, 1967): 1107-13. doi:10.1002/aic.690130613.
2: Najafi, Hamidreza, Babak Maghbooli, and Mohammad Amin Sobati. “Prediction of True Critical Volume of Multi-Component Mixtures: Extending Fast Estimation Methods.” Fluid Phase Equilibria 386 (January 25, 2015): 13-29. doi:10.1016/j.fluid.2014.11.008.

Examples

1-butanol/benzene 0.4271/0.5729 mixture, Vcm = 268.096 mL/mol.

>>> Chueh_Prausnitz_Vc([0.4271, 0.5729], [0.000273, 0.000256], [[0, 5.61847], [5.61847, 0]])
0.00026620503424517445

chemicals.critical.modified_Wilson_Vc(zs, Vcs, Aijs)[source]¶

Calculates critical volume of a mixture according to mixing rules in [1] with parameters. Equation

V_{cm} = \sum_i x_i V_{ci} + C\sum_i x_i \ln \left(x_i + \sum_j x_j A_{ij}\right)V_{ref}

For a binary mxiture, this simplifies to:

V_{cm} = x_1 V_{c1} + x_2 V_{c2} + C[x_1 \ln(x_1 + x_2A_{12}) + x_2\ln(x_2 + x_1 A_{21})]

Parameters

zsfloat: Mole fractions of all components
Vcsfloat: Critical volumes of all components, [m^3/mol]
Aijsmatrix: Interaction parameters, [cm^3/mol]

Returns

Vcmfloat: Critical volume of the mixture, [m^3/mol]

Notes

The equation and original article has been reviewed. All parameters, even if zero, must be given to this function. C = -2500

All parameters, even if zero, must be given to this function. nu parameters are in cm^3/mol, but are converted to m^3/mol inside the function

References

1: Teja, Amyn S., Kul B. Garg, and Richard L. Smith. “A Method for the Calculation of Gas-Liquid Critical Temperatures and Pressures of Multicomponent Mixtures.” Industrial & Engineering Chemistry Process Design and Development 22, no. 4 (1983): 672-76.
2: Najafi, Hamidreza, Babak Maghbooli, and Mohammad Amin Sobati. “Prediction of True Critical Temperature of Multi-Component Mixtures: Extending Fast Estimation Methods.” Fluid Phase Equilibria 392 (April 25, 2015): 104-26. doi:10.1016/j.fluid.2015.02.001.

Examples

1-butanol/benzene 0.4271/0.5729 mixture, Vcm = 268.096 mL/mol.

>>> modified_Wilson_Vc([0.4271, 0.5729], [0.000273, 0.000256],
... [[0, 0.6671250], [1.3939900, 0]])
0.0002664335032706881

Critical Properties (chemicals.critical)¶

Critical Temperature ¶

Critical Pressure ¶

Critical Volume ¶

Critical Compressibility Factor ¶

Critical Property Relationships ¶

Critical Temperature of Mixtures ¶

Critical Volume of Mixtures ¶

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