Isobutane

Formula: C₄H₁₀
Molecular weight: 58.1222
IUPAC Standard InChI: InChI=1S/C4H10/c1-4(2)3/h4H,1-3H3
IUPAC Standard InChIKey: NNPPMTNAJDCUHE-UHFFFAOYSA-N
CAS Registry Number: 75-28-5
Chemical structure:
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Other names: Propane, 2-methyl-; Trimethylmethane; 1,1-Dimethylethane; 2-Methylpropane; iso-C4H10; i-Butane; UN 1969; R 600a; tert-Butane; A 31; Methylpropane; A 31 (hydrocarbon)
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Gas phase thermochemistry data

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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
Δ_fH°_gas	-134.2 ± 0.63	kJ/mol	Ccb	Pittam and Pilcher, 1972	ALS
Δ_fH°_gas	-135.6 ± 0.54	kJ/mol	Cm	Prosen, Maron, et al., 1951	see Prosen and Rossini, 1945, Rossini, 1935; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-2869.0 ± 0.59	kJ/mol	Ccb	Pittam and Pilcher, 1972	Corresponding Δ_fHº_gas = -134.2 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-2867.6 ± 0.46	kJ/mol	Cm	Prosen, Maron, et al., 1951	see Prosen and Rossini, 1945, Rossini, 1935; Corresponding Δ_fHº_gas = -135.6 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
34.81	50.	Chen S.S., 1975	Recommended values are in good agreement with those calculated by [ Pitzer K.S., 1946].; GT
47.28	100.
60.29	150.
71.84	200.
89.91	273.15
96.65	298.15
97.15	300.
124.43	400.
149.24	500.
170.37	600.
188.28	700.
203.64	800.
216.94	900.
228.45	1000.
238.49	1100.
247.15	1200.
254.72	1300.
261.29	1400.
267.02	1500.

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
82.30 ± 0.06	243.15	Ernst G., 1970	Other experimental values of heat capacity [ Sage B.H., 1937, Sage B.H., 1938] are less accurate, see [ Chen S.S., 1975]. Please also see Dailey B.P., 1943, Wacker P.F., 1947.; GT
89.97 ± 0.06	273.15
95.21 ± 0.10	293.15
100.67 ± 0.10	313.15
106.37 ± 0.11	333.15
109.66	347.6
111.74 ± 0.11	353.15
112.55	359.4
119.62	387.5
137.03	452.5
152.93	520.9
161.29	561.7
169.70	605.3
185.18	692.7

References

Go To: Top, Gas phase thermochemistry data, Notes

Pittam and Pilcher, 1972
Pittam, D.A.; Pilcher, G., Measurements of heats of combustion by flame calorimetry. Part 8.-Methane, ethane, propane, n-butane and 2-methylpropane, J. Chem. Soc. Faraday Trans. 1, 1972, 68, 2224-2229. [all data]

Prosen, Maron, et al., 1951
Prosen, E.J.; Maron, F.W.; Rossini, F.D., Heats of combustion, formation, and insomerization of ten C₄ hydrocarbons, J. Res. NBS, 1951, 46, 106-112. [all data]

Prosen and Rossini, 1945
Prosen, E.J.; Rossini, F.D., Heats of formation and combustion of 1,3-butadiene and styrene, J. Res. NBS, 1945, 34, 59-63. [all data]

Rossini, 1935
Rossini, F.D., Heat of combustion of isobutane, J. Res. NBS, 1935, 15, 357-361. [all data]

Chen S.S., 1975
Chen S.S., Ideal gas thermodynamic properties and isomerization of n-butane and isobutane, J. Phys. Chem. Ref. Data, 1975, 4, 859-869. [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]

Ernst G., 1970
Ernst G., Ideal and real gas state heat capacities Cp of C3H8, i-C4H10, C2F5Cl, CH2ClCF3, CF2ClCFCl2, and CHF2Cl, J. Chem. Thermodyn., 1970, 2, 787-791. [all data]

Sage B.H., 1937
Sage B.H., Phase equilibria in hydrocarbon systems. XX. Isobaric heat capacity of gaseous propane, n-butane, isobutane, and n-pentane, Ind. Eng. Chem., 1937, 29, 1309-1314. [all data]

Sage B.H., 1938
Sage B.H., Phase equilibrium in hydrocarbon systems. Thermodynamic properties of isobutane, Ind. Eng. Chem., 1938, 30, 673-681. [all data]

Dailey B.P., 1943
Dailey B.P., Heat capacities and hindered rotation in n-butane and isobutane, J. Am. Chem. Soc., 1943, 65, 44-46. [all data]

Wacker P.F., 1947
Wacker P.F., Heat capacities of gaseous oxygen, isobutane, and 1-butene from -30 to +90 C, J. Res. Nat. Bur. Stand., 1947, 38, 651-659. [all data]

Notes

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Symbols used in this document:

C_p,gas Constant pressure heat capacity of gas

Δ_cH°_gas Enthalpy of combustion of gas at standard conditions

Δ_fH°_gas Enthalpy of formation of gas at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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C_p,gas	Constant pressure heat capacity of gas
Δ_cH°_gas	Enthalpy of combustion of gas at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions