Octane
- Formula: C8H18
- Molecular weight: 114.2285
- IUPAC Standard InChI: InChI=1S/C8H18/c1-3-5-7-8-6-4-2/h3-8H2,1-2H3
- IUPAC Standard InChIKey: TVMXDCGIABBOFY-UHFFFAOYSA-N
- CAS Registry Number: 111-65-9
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript. - Isotopologues:
- Other names: n-Octane; n-C8H18; Oktan; Oktanen; Ottani; UN 1262
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Gas phase thermochemistry data
Go To: Top, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled as indicated in comments:
DRB - Donald R. Burgess, Jr.
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | -49.88 | kcal/mol | N/A | Good, 1972 | Value computed using ΔfHliquid° value of -250.3±1.8 kj/mol from Good, 1972 and ΔvapH° value of 41.6 kj/mol from Prosen and Rossini, 1945.; DRB |
| ΔfH°gas | -49.82 ± 0.16 | kcal/mol | Ccb | Prosen and Rossini, 1945 | see Prosen and Rossini, 1944; ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas | 111.63 ± 0.22 | cal/mol*K | N/A | Scott D.W., 1974 | This reference does not contain the original experimental data. Experimental entropy value is based on the results [ Messerly J.F., 1967] for S(liquid).; GT |
Constant pressure heat capacity of gas
| Cp,gas (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 55.63 ± 0.11 | 385.65 | Hossenlopp I.A., 1981 | Please also see Barrow G.M., 1951.; GT |
| 57.11 ± 0.11 | 398.15 | ||
| 58.000 | 405.7 | ||
| 59.89 ± 0.12 | 423.15 | ||
| 62.86 ± 0.13 | 448.15 | ||
| 64.699 | 462.5 | ||
| 65.69 ± 0.13 | 473.15 | ||
| 68.35 ± 0.14 | 498.15 | ||
| 70.600 | 522.7 | ||
| 70.98 ± 0.14 | 523.15 |
Constant pressure heat capacity of gas
| Cp,gas (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 34.601 | 200. | Scott D.W., 1974, 2 | Recommended values were obtained from the consistent correlation scheme for alkanes [ Scott D.W., 1974, Scott D.W., 1974, 2]. This approach gives a better agreement with experimental data than the statistical thermodynamics calculation [ Pitzer K.S., 1944, Pitzer K.S., 1946].; GT |
| 41.991 | 273.15 | ||
| 44.88 ± 0.1 | 298.15 | ||
| 45.100 | 300. | ||
| 57.299 | 400. | ||
| 68.549 | 500. | ||
| 78.100 | 600. | ||
| 86.099 | 700. | ||
| 92.801 | 800. | ||
| 98.401 | 900. | ||
| 103.10 | 1000. | ||
| 107.20 | 1100. | ||
| 110.70 | 1200. | ||
| 114.00 | 1300. | ||
| 117.00 | 1400. | ||
| 119.00 | 1500. |
References
Go To: Top, Gas phase thermochemistry data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Good, 1972
Good, W.D.,
The enthalpies of combustion and formation of n-octane and 2,2,3,3-tetramethylbutane,
J. Chem. Thermodyn., 1972, 4, 709-714. [all data]
Prosen and Rossini, 1945
Prosen, E.J.; Rossini, F.D.,
Heats of combustion and formation of the paraffin hydrocarbons at 25° C,
J. Res. NBS, 1945, 263-267. [all data]
Prosen and Rossini, 1944
Prosen, E.J.; Rossini, F.D.,
Heats of combustion of eight normal paraffin hydrocarbons in the liquid state,
J. Res. NBS, 1944, 33, 255-272. [all data]
Scott D.W., 1974
Scott D.W.,
Correlation of the chemical thermodynamic properties of alkane hydrocarbons,
J. Chem. Phys., 1974, 60, 3144-3165. [all data]
Messerly J.F., 1967
Messerly J.F.,
Low-temperature thermal data for n-pentane, n-heptadecane, and n-octadecane. Revised thermodynamic functions for the n-alkanes, C5-C18,
J. Chem. Eng. Data, 1967, 12, 338-346. [all data]
Hossenlopp I.A., 1981
Hossenlopp I.A.,
Vapor heat capacities and enthalpies of vaporization of five alkane hydrocarbons,
J. Chem. Thermodyn., 1981, 13, 415-421. [all data]
Barrow G.M., 1951
Barrow G.M.,
Experimental vapor heat capacities and heats of vaporization of seven octanes,
J. Am. Chem. Soc., 1951, 73, 1824-1826. [all data]
Scott D.W., 1974, 2
Scott D.W.,
Chemical Thermodynamic Properties of Hydrocarbons and Related Substances. Properties of the Alkane Hydrocarbons, C1 through C10 in the Ideal Gas State from 0 to 1500 K. U.S. Bureau of Mines, Bulletin 666, 1974. [all data]
Pitzer K.S., 1944
Pitzer K.S.,
Thermodynamics of gaseous paraffins. Specific heat and related properties,
Ind. Eng. Chem., 1944, 36, 829-831. [all data]
Pitzer K.S., 1946
Pitzer K.S.,
The entropies and related properties of branched paraffin hydrocarbons,
Chem. Rev., 1946, 39, 435-447. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, References
- Symbols used in this document:
Cp,gas Constant pressure heat capacity of gas S°gas Entropy of gas at standard conditions ΔfH°gas Enthalpy of formation of gas at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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