# CuO: enthalpy of formation

> Enthalpy of formation of CuO: 19 literature value(s) with sources, pages and quotes and DFT values (Materials Project / OQMD), from ORCHID.

HTML: https://data.orchid-project.org/compounds/CuO.html · Markdown: https://data.orchid-project.org/compounds/CuO.md

19 accepted literature formation-enthalpy value(s) (experimental 13, model 6); experimental median -77.885 kJ/mol-atom (n = 13); Materials Project -90.966 kJ/mol-atom (mp-aaaaacnc); OQMD -80.231 kJ/mol-atom (oqmd-1343583).

Systems: [Cu–O](https://data.orchid-project.org/systems/CU-O.html)

## Literature values

Table: Enthalpy of formation of CuO reported in the literature (19)

| Value | Phase as printed | T (K) | Class | Method | System | Source | Location | Quote |
|---:|---|---:|---|---|---|---|---|---|
| -80.855 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Nufiez 1969_ | Table 8, p. 13, row 10; `ORC-ALFTX6OZRM.1e7619` |  |
| -80.855 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Nufiez 1969_ | Table 8, p. 13, row 12; `ORC-UQ5FDHCSKH` |  |
| -80.54 kJ/mol-atom | CuO | 295 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites H 1932_ | Table 8, p. 13, row 3; `ORC-J56QLHWYW7` |  |
| -78.535 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Nufiez 1969_ | Table 8, p. 13, row 10; `ORC-ALFTX6OZRM.b67909` |  |
| -78.535 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Nufiez 1969_ | Table 8, p. 13, row 11; `ORC-I5UR2MQHUO` |  |
| -77.885 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Mah 1967_ | Table 8, p. 13, row 8; `ORC-AJGT674S4D.aad2e0` |  |
| -77.885 kJ/mol-atom | CuO | 298.15 | experimental | React. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Mah 1967_ | Table 8, p. 13, row 9; `ORC-QQXJ6OCZ6G` |  |
| -77.74 kJ/mol-atom | CuO | 298.15 | experimental | Aq. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Thomsen 1883_ | Table 8, p. 13, row 2; `ORC-GMNQNEO2HB` |  |
| -77.74 kJ/mol-atom | CuO | 298.15 | experimental | Aq. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Thomsen 1883_ | Table 8, p. 13, row 1; `ORC-T4WZFE2TJJ.006290` |  |
| -76.15 kJ/mol-atom | CuO | 293 | experimental | Sol. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites ref. 34Bil_ | Table 8, p. 13, row 7; `ORC-4TQ3RYV4BP` |  |
| -76.15 kJ/mol-atom | CuO | 293 | experimental | Sol. Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites ref. 34Bil_ | Table 8, p. 13, row 6; `ORC-LGOKEWXJHR.e36160` |  |
| -69.08 kJ/mol-atom | CuO | 298.15 | experimental | Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Wrhler 1934_ | Table 8, p. 13, row 5; `ORC-PYVAEHKD5K` |  |
| -69.08 kJ/mol-atom | CuO | 298.15 | experimental | Cal. | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Wrhler 1934_ | Table 8, p. 13, row 4; `ORC-UEENQAKLM2.d6b8e9` |  |
| -78.03 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Chase 1985_ | Table 8, p. 13, row 14; `ORC-C7MXYNKNHW` |  |
| -78.03 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Chase 1985_ | Table 8, p. 13, row 13; `ORC-XCCWO6H7LI.fa10e4` |  |
| -77.595 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994 | Table 8, p. 13, row 18; `ORC-QZDH5SGEEG` |  |
| -77.595 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994 | Table 8, p. 13, row 17; `ORC-SNTTKLS5GR.ce4045` |  |
| -77.015 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Boud 1991_ | Table 8, p. 13, row 16; `ORC-LAWLJGIQGF` |  |
| -77.015 kJ/mol-atom | CuO | 298.15 | model | Assessed | [Cu–O](https://data.orchid-project.org/systems/CU-O.html) | [1] Hallstedt 1994; _cites Boud 1991_ | Table 8, p. 13, row 15; `ORC-UDWXTWFN6Y.049c73` |  |

### Uncertainty budget

Components kept separate, in the value's unit (literature [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md), [UNCERTAINTY_CALIBRATION.md](https://data.orchid-project.org/literature/UNCERTAINTY_CALIBRATION.md)): effective = max(sqrt(max(printed, reading, method)^2 + composition^2 + conversion^2), scatter). The method floor is the robust between-study scatter of the method class in ORCHID (calibrated) or a documented prior; printed values and printed uncertainties are unchanged.

Table: Uncertainty budget of the literature values of CuO

| Value | Unit | Printed | Reading | Method (class, basis) | Composition | Scatter | Conversion | Effective |
|---:|---|---:|---:|---|---:|---:|---:|---:|
| -80.855 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -80.855 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -80.54 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -78.535 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -78.535 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -77.885 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -77.885 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -77.74 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -77.74 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -76.15 | kJ/mol-atom |  | 0.025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -76.15 | kJ/mol-atom |  | 0.025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -69.08 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -69.08 | kJ/mol-atom |  | 0.0025 | 3.2 (solution_reaction_calorimetry, calibrated) |  |  |  | 3.2 |
| -78.03 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -78.03 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -77.595 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -77.595 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -77.015 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |
| -77.015 | kJ/mol-atom |  | 0.0025 | 3.9 (model_calculated, calibrated) |  |  |  | 3.9 |

## DFT formation energies

Lowest-energy entries at this composition. Materials Project and OQMD use different energy references and are never averaged. 1 eV/atom = 96.485 kJ/mol-atom.

Table: DFT formation energy of CuO

| Source | Entry | kJ/mol-atom | eV/atom | Space group | E above hull (kJ/mol-atom) | E above hull (eV/atom) | Theoretical |
|---|---|---:|---:|---|---:|---:|---|
| Materials Project | mp-aaaaacnc | -90.966 | -0.942795 | P4_2/mmc | 0 | 0 | yes |
| OQMD | oqmd-1343583 | -80.231 | -0.831534 | P42/mmc | 0 | 0 | yes |

DFT sources: A. Jain et al., Commentary: The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002. [doi:10.1063/1.4812323](https://doi.org/10.1063/1.4812323) (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501-1509; S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010. [doi:10.1007/s11837-013-0755-4](https://doi.org/10.1007/s11837-013-0755-4) (CC BY 4.0); 

## Sources

1. B. Hallstedt, D. Risold, L. J. Gauckler, Thermodynamic assessment of the copper-oxygen system, JPE 15, 483-499 (1994). [doi:10.1007/bf02649399](https://doi.org/10.1007/bf02649399)

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735569
- R. Arróyave, J. Saal, D. Shin, ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735943
- R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); G. Kim, S. V. Meschel, P. Nash, W. Chen, Experimental formation enthalpies for intermetallic phases and other inorganic compounds, Scientific Data 4 (2017) 170162, https://doi.org/10.1038/sdata.2017.162; B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file.

Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

```bibtex
@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_dft_benchmark_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735943},
  url       = {https://doi.org/10.5281/zenodo.23735943},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}
```

---

Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite ORCHID ([CITATION.cff](https://data.orchid-project.org/CITATION.cff)) and the original sources. Quotes are short excerpts kept so that each value can be checked; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full text are not redistributed. Field reference: [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt). Found an error? The report link of a value (Markdown: its id, ORC-..., in the Location column) opens a pre-filled GitHub issue, https://github.com/orchid-calphad/orchid-data/issues/new?template=report-value-error.yml&record_id=\<id>, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).