Documentation / ChEDL data
ChEDL data
Cheméo serves values from nine data tables of the chemicals library, version 1.5.2, part of the Chemical Engineering Design Library (ChEDL) by Caleb Bell, distributed under the MIT licence (notice below).
ChEDL collects published tables.
On Cheméo, each value is cited from the publication it comes from, as ChEDL chemicals 1.5.2, from <citation>, with a link to the publication.
Values found wrong at the source are listed on Corrected source values.
The file
The tables were read from chemicals-1.5.2-py3-none-any.whl, downloaded from PyPI, sha256 f85ef7f36e77fee634686c26562929ee61026cd548d89cebd57b2251ca843d6e.
The wheel is opened as a zip archive: the library is never installed, imported or executed.
A manifest lists every table read, each with its own sha256, and a table whose content changed causes the whole file to be refused.
The tables
Nine tables were retained.
Each appears on Cheméo as its own source, named ChEDL: ....
| source | values | rows | notes |
|---|---|---|---|
| IUPAC "Vapor-Liquid Critical Properties of Elements and Compounds", parts 2 to 11, J. Chem. Eng. Data 1995 to 2009 | Tc, Pc, Vc, Zc | 810 | evaluated experimental data; each row cites its part, and each part is its own source |
| Mathews, Chem. Rev. 1972 | Tc, Pc, Vc, Zc | 120 | inorganic substances |
| Horstmann et al., Fluid Phase Equilib. 2005 (PSRK revision IV) | Tc, Pc, Vc, acentric factor | 995 | ChEDL calls it "a compilation of experimental and estimated data": the estimates are not flagged |
| Passut and Danner, Ind. Eng. Chem. Process Des. Dev. 1973 | Tc, Pc, acentric factor | 192 | an older compilation; its constants may come from the API Technical Data Book |
| Staveley, Lobo and Calado, Cryogenics 1981 | triple point temperature and pressure | 189 | the pressure uncertainty is kept when the table gives one |
| Active Thermochemical Tables 1.112 (Argonne), Ruscic et al. 2005 | gas-phase enthalpy of formation at 298.15 K | 595 | ions are left out (288 rows); the uncertainty is ATcT's 95% interval |
| Bradley, Williams and Lang, Open Melting Point Dataset, 2014 (CC0) | melting point | 11,549 | ChEDL stores the median when the dataset has several values |
| Jasper, J. Phys. Chem. Ref. Data 1972 | surface tension, linear in T | 522 | transcribed through Lange's Handbook; the values are Jasper's |
| Hankinson and Thomson, AIChE J. 1979 (COSTALD) | SRK acentric factor, characteristic volume, Rackett parameter | 192 |
The full citations are given in the Sources list of each compound page.
Differences from the tables
- Units. The values were converted to the units of Cheméo (kPa, m³/kmol, kJ/mol). Jasper's σ = a − b·(T − 273.15), in mN/m, was rewritten exactly in the DIPPR 100 form, in N/m.
- Values left out: empty cells; a 0 given for a critical constant, a triple point or a melting point, which is not a value; the Jasper rows without a temperature range (32 rows); the ATcT ions.
- Names. The names were normalised (Unicode NFKC, spaces). A name damaged in transcription was not used, while its values were: glyph garbage in Jasper's names, and OCR spacing inside systematic names, mostly in Staveley's ("2, 2-Dimethylbutane", "Perfluoro- cyclobutane"); 38 records in all.
- One correction. The IUPAC table of ChEDL swaps the CAS numbers of cyclohexane and methylcyclopentane (part 5). The names and values agree, by name, with the PSRK and Passut-Danner tables, so each row was put back on its own CAS number. The correction is matched on both the CAS number and the name.
Placement of a row on a compound
The rows carry a CAS number and a name, but no structure. A row is placed on the Cheméo compound to which its CAS number resolves in the identity registry of Cheméo, and its name is checked. A row whose CAS number belongs to two compounds is not placed.
Where the CAS number in the table is wrong but the name is right, the row is placed by its name. Iodine, hydrogen sulfide and phosphine carry the CAS numbers of potassium iodide, sulfur and phosphorus, and Staveley's "Oxygen" that of atomic oxygen. Two such rows name a less specific compound than their CAS number: Jasper's "2-Butene" carries the CAS number of (E)-2-butene, and "D-Limonene" that of (S)-limonene. Both were placed on the compound of the name.
165 compounds not previously on Cheméo received a page through these tables, 164 of them for a measured melting point from the Bradley dataset.
Data not imported
A value was imported only when its original source can be named and the terms of that source allow redistribution. The following were left out:
- Commercial handbooks, and the tables derived from them: the CRC Handbook, the collections of Yaws, Perry's Handbook (DIPPR, whose terms forbid redistribution), the VDI Heat Atlas, Poling's Properties of Gases and Liquids, Landolt-Börnstein, the API Technical Data Book, and the compilations republishing DIPPR values.
- Non-commercial terms: CAS Common Chemistry (CC BY-NC).
- Predictions: Wilson-Jasperson, Fedors, Joback and others; Cheméo computes its own.
- Data already on Cheméo: the heat capacities of Zábranský, NIST-JANAF, the WebBook values.
- No source per value: the constants of CoolProp, Wikidata, Bell 2018.
- Deferred: the correlation forms not yet available on Cheméo (Wagner-McGarry, Mulero and Cachadiña, Somayajulu), and the liquid-phase table of ATcT.
Licence
The chemicals library is distributed under the MIT licence:
MIT License
Copyright (C) 2016, 2017, 2018, 2019, 2020, 2021 Caleb Bell <Caleb.Andrew.Bell@gmail.com>
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