Heptane, 3-methyl-
- Formula: C8H18
- Molecular weight: 114.2285
- IUPAC Standard InChI: InChI=1S/C8H18/c1-4-6-7-8(3)5-2/h8H,4-7H2,1-3H3
- IUPAC Standard InChIKey: LAIUFBWHERIJIH-UHFFFAOYSA-N
- CAS Registry Number: 589-81-1
- 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:
- Stereoisomers:
- Other names: 3-Methylheptane; 2-Ethylhexane
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Gas phase thermochemistry data
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, 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:
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 | -212.6 ± 1.1 | kJ/mol | Ccb | Prosen and Rossini, 1945 | ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas | 465.89 ± 0.84 | J/mol*K | N/A | Finke H.L., 1973 | GT |
Constant pressure heat capacity of gas
| Cp,gas (J/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 132.67 | 200. | Scott D.W., 1974 | Recommended values were obtained from the consistent correlation scheme for alkanes [ Scott D.W., 1974, 2, Scott D.W., 1974]. This approach gives a good agreement with experimental data available for alkanes. However, large uncertainties could be expected at high temperatures.; GT |
| 172.30 | 273.15 | ||
| 185.8 ± 0.5 | 298.15 | ||
| 186.82 | 300. | ||
| 240.16 | 400. | ||
| 287.82 | 500. | ||
| 328.03 | 600. | ||
| 362.33 | 700. | ||
| 391.20 | 800. | ||
| 415.47 | 900. | ||
| 436.39 | 1000. | ||
| 454.38 | 1100. | ||
| 470.28 | 1200. | ||
| 485.34 | 1300. | ||
| 497.90 | 1400. | ||
| 510.45 | 1500. |
Condensed phase thermochemistry data
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, 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:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°liquid | -252.5 ± 1.1 | kJ/mol | Ccb | Prosen and Rossini, 1945 | ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°liquid | -5468.2 ± 1.3 | kJ/mol | Ccb | Prosen and Rossini, 1945 | Corresponding ΔfHºliquid = -252.4 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°liquid | 362.6 | J/mol*K | N/A | Finke and Messerly, 1973 | Thermodynamic properties calculated from a Debye function at 10 K.; DH |
Constant pressure heat capacity of liquid
| Cp,liquid (J/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 250.20 | 298.15 | Finke and Messerly, 1973 | T = 10 to 380 K.; DH |
| 249.66 | 298.15 | Osborne and Ginnings, 1947 | T = 293 to 318 K.; DH |
Reaction thermochemistry data
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.
Individual Reactions
=
By formula: C8H18 = C8H18
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | -2.6 ± 0.79 | kJ/mol | Ciso | Prosen and Rossini, 1945, 2 | liquid phase; Calculated from ΔHc |
+
=
By formula: C8H16 + H2 = C8H18
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | -124.6 ± 0.6 | kJ/mol | Chyd | Rogers, Dejroongruang, et al., 1992 | liquid phase; solvent: Cyclohexane |
=
By formula: C8H18 = C8H18
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 1.86 ± 0.42 | kJ/mol | Eqk | Roganov, Kabo, et al., 1972 | gas phase; At 1368 K |
References
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
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]
Finke H.L., 1973
Finke H.L.,
3-Methylpentane and 3-methylheptane: low-temperature thermodynamic properties,
J. Chem. Thermodyn., 1973, 5, 247-257. [all data]
Scott D.W., 1974
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]
Scott D.W., 1974, 2
Scott D.W.,
Correlation of the chemical thermodynamic properties of alkane hydrocarbons,
J. Chem. Phys., 1974, 60, 3144-3165. [all data]
Finke and Messerly, 1973
Finke, H.L.; Messerly, J.F.,
3-Methylpentane and 3-methylheptane: low-temperature thermodynamic properties,
J. Chem. Thermodynam., 1973, 5, 247-257. [all data]
Osborne and Ginnings, 1947
Osborne, N.S.; Ginnings, D.C.,
Measurements of heat of vaporization and heat capacity of a number of hydrocarbons,
J. Res. NBS, 1947, 39, 453-477. [all data]
Prosen and Rossini, 1945, 2
Prosen, E.J.; Rossini, F.D.,
Heats of isomerization of the 18 octanes,
J. Res. NBS, 1945, 34, 163-174. [all data]
Rogers, Dejroongruang, et al., 1992
Rogers, D.W.; Dejroongruang, K.; Samuel, S.D.; Fang, W.; Zhao, Y.,
Enthalpies of hydrogenation of the octenes and the methylheptenes,
J. Chem. Thermodyn., 1992, 24, 561-565. [all data]
Roganov, Kabo, et al., 1972
Roganov, G.N.; Kabo, G.Ya.; Andreevskii, D.N.,
Thermodynamics of the isomerization of methylpentanes and methylheptanes,
Neftekhimiya, 1972, 12, 495-500. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, References
- Symbols used in this document:
Cp,gas Constant pressure heat capacity of gas Cp,liquid Constant pressure heat capacity of liquid S°gas Entropy of gas at standard conditions S°liquid Entropy of liquid at standard conditions ΔcH°liquid Enthalpy of combustion of liquid at standard conditions ΔfH°gas Enthalpy of formation of gas at standard conditions ΔfH°liquid Enthalpy of formation of liquid at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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