Methane

Formula: CH₄
Molecular weight: 16.0425
IUPAC Standard InChI: InChI=1S/CH4/h1H4
IUPAC Standard InChIKey: VNWKTOKETHGBQD-UHFFFAOYSA-N
CAS Registry Number: 74-82-8
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.
Other names: Marsh gas; Methyl hydride; CH4; Fire Damp; R 50; Biogas; R 50 (refrigerant)
Permanent link for this species. Use this link for bookmarking this species for future reference.
Information on this page:
Other data available:
- Phase change data
- Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 100, reactions 101 to 112
- Henry's Law data
- IR Spectrum
- Mass spectrum (electron ionization)
- Vibrational and/or electronic energy levels
- Fluid Properties
Data at other public NIST sites:
Options:
- Switch to calorie-based units

Data at NIST subscription sites:

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Gas phase thermochemistry data

Go To: Top, Gas phase ion energetics data, Ion clustering data, References, Notes

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
Δ_fH°_gas	-74.87	kJ/mol	Review	Chase, 1998	Data last reviewed in March, 1961
Δ_fH°_gas	-74.6 ± 0.3	kJ/mol	Review	Manion, 2002	adopted recommendation of Gurvich, Veyts, et al., 1991; DRB
Δ_fH°_gas	-74.5 ± 0.4	kJ/mol	Ccb	Pittam and Pilcher, 1972	ALS
Δ_fH°_gas	-74.85 ± 0.31	kJ/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; ALS
Δ_fH°_gas	-73.4 ± 1.1	kJ/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -75.19 kJ/mol; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-890.7 ± 0.4	kJ/mol	Ccb	Pittam and Pilcher, 1972	Corresponding Δ_fHº_gas = -74.48 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-890.35 ± 0.30	kJ/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; Corresponding Δ_fHº_gas = -74.822 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-891.8 ± 1.1	kJ/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -887.3 ± 1.0 kJ/mol; Corresponding Δ_fHº_gas = -73.39 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-890.16 ± 0.30	kJ/mol	Cm	Rossini, 1931	Corresponding Δ_fHº_gas = -75.010 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_gas	188.66 ± 0.42	J/mol*K	N/A	Colwell J.H., 1963	The calorimetric value is significantly higher than the statistically calculated entropy, 186.26 J/molK, which remains the best value for use in thermodynamic calculations [ Vogt G.J., 1976, Friend D.G., 1989, Gurvich, Veyts, et al., 1989]. Earlier the value of 185.3 J/molK was calculated from experimental data [ Giauque W.F., 1931]. The value of S(298.15 K)=185.94 J/mol*K was obtained by high accuracy ab initio calculation [ East A.L.L., 1997].; GT
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	186.25	J/mol*K	Review	Chase, 1998	Data last reviewed in March, 1961

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
34.92 ± 0.25	279.	Halford J.O., 1957	GT

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
33.28	100.	Gurvich, Veyts, et al., 1989	p=1 bar. Because of more precise method of calculation, the recommended values are more accurate, especially at high temperatures, than those obtained by [ McDowell R.S., 1963] and often regarded as reference data [ Friend D.G., 1989].; GT
33.51	200.
35.69	298.15
35.76	300.
40.63	400.
46.63	500.
52.74	600.
58.60	700.
64.08	800.
69.14	900.
73.75	1000.
77.92	1100.
81.68	1200.
85.07	1300.
88.11	1400.
90.86	1500.
93.33	1600.
95.58	1700.
97.63	1800.
99.51	1900.
101.24	2000.
102.83	2100.
104.31	2200.
105.70	2300.
107.00	2400.
108.23	2500.
109.39	2600.
110.50	2700.
111.56	2800.
112.57	2900.
113.55	3000.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
C_p = heat capacity (J/mol*K)
H° = standard enthalpy (kJ/mol)
S° = standard entropy (J/mol*K)
t = temperature (K) / 1000.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Temperature (K)	298. to 1300.	1300. to 6000.
A	-0.703029	85.81217
B	108.4773	11.26467
C	-42.52157	-2.114146
D	5.862788	0.138190
E	0.678565	-26.42221
F	-76.84376	-153.5327
G	158.7163	224.4143
H	-74.87310	-74.87310
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1961	Data last reviewed in March, 1961

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Ion clustering data, References, Notes

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to CH₄⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	12.61 ± 0.01	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	543.5	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	520.6	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
12.61 ± 0.01	PI	Berkowitz, Greene, et al., 1987	LBLHLM
12.6 ± 0.4	EI	Chatham, Hils, et al., 1984	LBLHLM
12.63 ± 0.02	EI	Plessis, Marmet, et al., 1983	LBLHLM
13.6	PE	Kimura, Katsumata, et al., 1981	LLK
12.75 ± 0.02	PE	Bieri, Burger, et al., 1977	LLK
12.82 ± 0.02	EI	Selim and El-Kholy, 1975	LLK
12.6	PE	Debies and Rabalais, 1975	LLK
12.6	PI	Rabalais, Debies, et al., 1974	LLK
12.8	EI	Morrison and Traeger, 1973	LLK
12.64	PE	Potts and Price, 1972	LLK
12.94 ± 0.04	EI	Finney and Harrison, 1972	LLK
12.51	PE	Bergmark, Rabalais, et al., 1972	LLK
~12.51	PE	Rabalais, Bergmark, et al., 1971	LLK
≤12.615 ± 0.010	PI	Chupka and Berkowitz, 1971	LLK
12.78	PE	Pullen, Carlson, et al., 1970	RDSH
12.75	PE	Brundle, Robin, et al., 1970	RDSH
≤12.70	EI	Lossing and Semeluk, 1969	RDSH
12.99 ± 0.05	EI	Williams and Hamill, 1968	RDSH
12.75 ± 0.05	TE	Villarejo, Stockbauer, et al., 1968	RDSH
12.9	CI	Cermak, 1968	RDSH
12.70	PE	Baker, Baker, et al., 1968	RDSH
12.55 ± 0.05	PI	Brehm, 1966	RDSH
12.704 ± 0.008	PI	Nicholson, 1965	RDSH
12.71 ± 0.02	PI	Dibeler, Krauss, et al., 1965	RDSH
13.00 ± 0.02	EI	Melton and Hamill, 1964	RDSH
13.6	PE	Bieri and Asbrink, 1980	Vertical value; LLK
13.6 ± 0.1	PE	Bieri, Burger, et al., 1977	Vertical value; LLK
13.60	EI	Harshbarger, Robin, et al., 1973	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C⁺	25. ± 2.	?	EI	Chatham, Hils, et al., 1984	LBLHLM
C⁺	19.56 ± 0.20	2H₂	EI	Plessis, Marmet, et al., 1983	LBLHLM
C⁺	≤25.2	?	EI	Morrison and Traeger, 1973	LLK
CH⁺	22.2 ± 0.4	?	EI	Chatham, Hils, et al., 1984	LBLHLM
CH⁺	19.11 ± 0.20	H^-+H₂	EI	Plessis, Marmet, et al., 1983	LBLHLM
CH⁺	19.87 ± 0.20	H+H₂	EI	Plessis, Marmet, et al., 1983	LBLHLM
CH⁺	22.4	H₂+H?	EI	Morrison and Traeger, 1973	LLK
CH₂⁺	15.1 ± 0.4	H₂	EI	Chatham, Hils, et al., 1984	LBLHLM
CH₂⁺	15.06 ± 0.02	H₂	EI	Plessis, Marmet, et al., 1983	LBLHLM
CH₂⁺	15.16 ± 0.02	H₂	PI	McCulloh and Dibeler, 1976	T = 0K; LLK
CH₂⁺	15.3	H₂	EI	Morrison and Traeger, 1973	LLK
CH₂⁺	15.19 ± 0.02	H₂	PI	Chupka, 1968	RDSH
CH₂⁺	15.16 ± 0.04	H₂	PI	Dibeler, Krauss, et al., 1965	RDSH
CH₃⁺	14.3 ± 0.4	H	EI	Chatham, Hils, et al., 1984	LBLHLM
CH₃⁺	13.25 ± 0.08	H^-	EI	Plessis, Marmet, et al., 1983	LBLHLM
CH₃⁺	14.01 ± 0.08	H	EI	Plessis, Marmet, et al., 1983	LBLHLM
CH₃⁺	14.30	H	PIPECO	Stockbauer, 1977	LLK
CH₃⁺	14.324 ± 0.003	H	PI	McCulloh and Dibeler, 1976	T = 0K; LLK
CH₃⁺	14.4	H	EI	Morrison and Traeger, 1973	LLK
CH₃⁺	14.30	H	EI	Lossing and Semeluk, 1970	RDSH
CH₃⁺	14.24 ± 0.05	H	EI	Williams and Hamill, 1968	RDSH
CH₃⁺	13.50 ± 0.05	H^-	PI	Chupka, 1968	RDSH
CH₃⁺	14.320 ± 0.004	H	PI	Chupka, 1968	RDSH
CH₃⁺	14.23 ± 0.05	H	PI	Brehm, 1966	RDSH
CH₃⁺	14.25 ± 0.02	H	PI	Dibeler, Krauss, et al., 1965	RDSH
H⁺	21.3 ± 0.3	CH₃	EI	Locht, Olivier, et al., 1979	LLK
H⁺	24.0 ± 0.5	CH₃	EI	Appell and Kubach, 1971	LLK

De-protonation reactions

CH₃^- + = Methane

By formula: CH₃^- + H⁺ = CH₄

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1743.6 ± 2.9	kJ/mol	D-EA	Ellison, Engelking, et al., 1978	gas phase; B
Δ_rH°	1749. ± 15.	kJ/mol	CIDT	Graul and Squires, 1990	gas phase; B
Δ_rH°	>1691.1 ± 0.42	kJ/mol	G+TS	Bohme, Lee-Ruff, et al., 1972	gas phase; B
Δ_rH°	1735.5	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeBr3; ; ΔS(EA)=9.3; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1709.8 ± 3.3	kJ/mol	H-TS	Ellison, Engelking, et al., 1978	gas phase; B
Δ_rG°	1715. ± 15.	kJ/mol	H-TS	Graul and Squires, 1990	gas phase; B
Δ_rG°	>1657.3	kJ/mol	IMRB	Bohme, Lee-Ruff, et al., 1972	gas phase; B
Δ_rG°	1704.1	kJ/mol	N/A	Check, Faust, et al., 2001	gas phase; FeBr3; ; ΔS(EA)=9.3; B

Ion clustering data

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, References, Notes

Data compiled as indicated in comments:
B - John E. Bartmess
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
RCD - Robert C. Dunbar

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

+ Methane = CH₄Br^-

By formula: Br^- + CH₄ = CH₄Br^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.0	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-9.50	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = ( • Methane )

By formula: CF₃⁺ + CH₄ = (CF₃⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	19.	kJ/mol	HPMS	Bennet and Field, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	78.7	J/mol*K	HPMS	Bennet and Field, 1972	gas phase; M

CH₄Cl^- + 2 Methane = C₂H₈Cl^-

By formula: CH₄Cl^- + 2CH₄ = C₂H₈Cl^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.6	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-12.8	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

CH₄F^- + 2 Methane = C₂H₈F^-

By formula: CH₄F^- + 2CH₄ = C₂H₈F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	24.7	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-1.5	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

CH₅⁺ + Methane = (CH₅⁺ • Methane )

By formula: CH₅⁺ + CH₄ = (CH₅⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29. ± 1.	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	31.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rH°	17.	kJ/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.5	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	87.0	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rS°	51.9	J/mol*K	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M

(CH₅⁺ • Methane ) + Methane = (CH₅⁺ • 2 Methane )

By formula: (CH₅⁺ • CH₄) + CH₄ = (CH₅⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	22. ± 1.	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	25.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rH°	6.3	kJ/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	104.	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	102.	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rS°	30.	J/mol*K	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M

(CH₅⁺ • 2 Methane ) + Methane = (CH₅⁺ • 3 Methane )

By formula: (CH₅⁺ • 2CH₄) + CH₄ = (CH₅⁺ • 3CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.1 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	17.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	93.7	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	109.	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M

(CH₅⁺ • 3 Methane ) + Methane = (CH₅⁺ • 4 Methane )

By formula: (CH₅⁺ • 3CH₄) + CH₄ = (CH₅⁺ • 4CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.6 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	16.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	99.2	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	111.	J/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M

(CH₅⁺ • 4 Methane ) + Methane = (CH₅⁺ • 5 Methane )

By formula: (CH₅⁺ • 4CH₄) + CH₄ = (CH₅⁺ • 5CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.7 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	104.	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(CH₅⁺ • 5 Methane ) + Methane = (CH₅⁺ • 6 Methane )

By formula: (CH₅⁺ • 5CH₄) + CH₄ = (CH₅⁺ • 6CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.3 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	106.	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(CH₅⁺ • 6 Methane ) + Methane = (CH₅⁺ • 7 Methane )

By formula: (CH₅⁺ • 6CH₄) + CH₄ = (CH₅⁺ • 7CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	11.2 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	111.	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(CH₅⁺ • 7 Methane ) + Methane = (CH₅⁺ • 8 Methane )

By formula: (CH₅⁺ • 7CH₄) + CH₄ = (CH₅⁺ • 8CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.5 ± 0.8	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	90.4	J/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M

(CH₅⁺ • 8 Methane ) + Methane = (CH₅⁺ • 9 Methane )

By formula: (CH₅⁺ • 8CH₄) + CH₄ = (CH₅⁺ • 9CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	6.44	kJ/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Hiraoka and Mori, 1989	gas phase; Entropy change calculated or estimated; M

C₂H₅⁺ + Methane = (C₂H₅⁺ • Methane )

By formula: C₂H₅⁺ + CH₄ = (C₂H₅⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	23.0	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rH°	28.	kJ/mol	PHPMS	Hiroka and Kebarle, 1975	gas phase; M
Δ_rH°	10.	kJ/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.9	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rS°	97.9	J/mol*K	PHPMS	Hiroka and Kebarle, 1975	gas phase; M
Δ_rS°	36.	J/mol*K	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M

(C₂H₅⁺ • Methane ) + Methane = (C₂H₅⁺ • 2 Methane )

By formula: (C₂H₅⁺ • CH₄) + CH₄ = (C₂H₅⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.92	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	67.4	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 2 Methane ) + Methane = (C₂H₅⁺ • 3 Methane )

By formula: (C₂H₅⁺ • 2CH₄) + CH₄ = (C₂H₅⁺ • 3CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.54	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	74.9	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 3 Methane ) + Methane = (C₂H₅⁺ • 4 Methane )

By formula: (C₂H₅⁺ • 3CH₄) + CH₄ = (C₂H₅⁺ • 4CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.46	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.0	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 4 Methane ) + Methane = (C₂H₅⁺ • 5 Methane )

By formula: (C₂H₅⁺ • 4CH₄) + CH₄ = (C₂H₅⁺ • 5CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.29	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.1	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 5 Methane ) + Methane = (C₂H₅⁺ • 6 Methane )

By formula: (C₂H₅⁺ • 5CH₄) + CH₄ = (C₂H₅⁺ • 6CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.25	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	81.2	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 6 Methane ) + Methane = (C₂H₅⁺ • 7 Methane )

By formula: (C₂H₅⁺ • 6CH₄) + CH₄ = (C₂H₅⁺ • 7CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.91	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	86.6	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 7 Methane ) + Methane = (C₂H₅⁺ • 8 Methane )

By formula: (C₂H₅⁺ • 7CH₄) + CH₄ = (C₂H₅⁺ • 8CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.79	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	87.9	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 8 Methane ) + Methane = (C₂H₅⁺ • 9 Methane )

By formula: (C₂H₅⁺ • 8CH₄) + CH₄ = (C₂H₅⁺ • 9CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.70	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.2	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₂H₅⁺ • 9 Methane ) + Methane = (C₂H₅⁺ • 10 Methane )

By formula: (C₂H₅⁺ • 9CH₄) + CH₄ = (C₂H₅⁺ • 10CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.99	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.	J/mol*K	N/A	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M

C₂H₈F^- + 3 Methane = C₃H₁₂F^-

By formula: C₂H₈F^- + 3CH₄ = C₃H₁₂F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	23.0	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-5.69	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₃H₇⁺ + Methane = (C₃H₇⁺ • Methane )

By formula: C₃H₇⁺ + CH₄ = (C₃H₇⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.8	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rH°	14.	kJ/mol	PHPMS	Hiraoka and Kebarle, 1976	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	72.8	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rS°	84.	J/mol*K	PHPMS	Hiraoka and Kebarle, 1976	gas phase; M

(C₃H₇⁺ • Methane ) + Methane = (C₃H₇⁺ • 2 Methane )

By formula: (C₃H₇⁺ • CH₄) + CH₄ = (C₃H₇⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.3	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.5	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 2 Methane ) + Methane = (C₃H₇⁺ • 3 Methane )

By formula: (C₃H₇⁺ • 2CH₄) + CH₄ = (C₃H₇⁺ • 3CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.46	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	77.0	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 3 Methane ) + Methane = (C₃H₇⁺ • 4 Methane )

By formula: (C₃H₇⁺ • 3CH₄) + CH₄ = (C₃H₇⁺ • 4CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.20	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	79.5	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 4 Methane ) + Methane = (C₃H₇⁺ • 5 Methane )

By formula: (C₃H₇⁺ • 4CH₄) + CH₄ = (C₃H₇⁺ • 5CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.20	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	87.4	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 5 Methane ) + Methane = (C₃H₇⁺ • 6 Methane )

By formula: (C₃H₇⁺ • 5CH₄) + CH₄ = (C₃H₇⁺ • 6CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.16	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	87.9	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 6 Methane ) + Methane = (C₃H₇⁺ • 7 Methane )

By formula: (C₃H₇⁺ • 6CH₄) + CH₄ = (C₃H₇⁺ • 7CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.04	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.2	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₃H₇⁺ • 7 Methane ) + Methane = (C₃H₇⁺ • 8 Methane )

By formula: (C₃H₇⁺ • 7CH₄) + CH₄ = (C₃H₇⁺ • 8CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.28	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	92.	J/mol*K	N/A	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M

C₃H₁₂F^- + 4 Methane = C₄H₁₆F^-

By formula: C₃H₁₂F^- + 4CH₄ = C₄H₁₆F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	20.9	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-9.04	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₄H₉⁺ + Methane = (C₄H₉⁺ • Methane )

By formula: C₄H₉⁺ + CH₄ = (C₄H₉⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.4	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	81.6	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • Methane ) + Methane = (C₄H₉⁺ • 2 Methane )

By formula: (C₄H₉⁺ • CH₄) + CH₄ = (C₄H₉⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.0	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	81.2	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 2 Methane ) + Methane = (C₄H₉⁺ • 3 Methane )

By formula: (C₄H₉⁺ • 2CH₄) + CH₄ = (C₄H₉⁺ • 3CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.92	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	82.4	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 3 Methane ) + Methane = (C₄H₉⁺ • 4 Methane )

By formula: (C₄H₉⁺ • 3CH₄) + CH₄ = (C₄H₉⁺ • 4CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.87	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	83.7	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 4 Methane ) + Methane = (C₄H₉⁺ • 5 Methane )

By formula: (C₄H₉⁺ • 4CH₄) + CH₄ = (C₄H₉⁺ • 5CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.25	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	81.2	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 5 Methane ) + Methane = (C₄H₉⁺ • 6 Methane )

By formula: (C₄H₉⁺ • 5CH₄) + CH₄ = (C₄H₉⁺ • 6CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.74	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	80.8	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 6 Methane ) + Methane = (C₄H₉⁺ • 7 Methane )

By formula: (C₄H₉⁺ • 6CH₄) + CH₄ = (C₄H₉⁺ • 7CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.58	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	82.4	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 7 Methane ) + Methane = (C₄H₉⁺ • 8 Methane )

By formula: (C₄H₉⁺ • 7CH₄) + CH₄ = (C₄H₉⁺ • 8CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.33	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.1	J/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M

(C₄H₉⁺ • 8 Methane ) + Methane = (C₄H₉⁺ • 9 Methane )

By formula: (C₄H₉⁺ • 8CH₄) + CH₄ = (C₄H₉⁺ • 9CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.78	kJ/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M

C₄H₁₆F^- + 5 Methane = C₅H₂₀F^-

By formula: C₄H₁₆F^- + 5CH₄ = C₅H₂₀F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	18.8	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-12.3	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₅H₂₀F^- + 6 Methane = C₆H₂₄F^-

By formula: C₅H₂₀F^- + 6CH₄ = C₆H₂₄F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	17.6	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-13.6	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₅MnO₅⁺ + Methane = (C₅MnO₅⁺ • Methane )

By formula: C₅MnO₅⁺ + CH₄ = (C₅MnO₅⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.	kJ/mol	ICRCD	Hop and McMahon, 1991	gas phase; Ar collision gas, Δ_rH<; M

C₆H₂₄F^- + 7 Methane = C₇H₂₈F^-

By formula: C₆H₂₄F^- + 7CH₄ = C₇H₂₈F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	13.8	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-12.4	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₇H₂₈F^- + 8 Methane = C₈H₃₂F^-

By formula: C₇H₂₈F^- + 8CH₄ = C₈H₃₂F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	12.1	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-15.3	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₈H₃₂F^- + 9 Methane = C₉H₃₆F^-

By formula: C₈H₃₂F^- + 9CH₄ = C₉H₃₆F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	9.62	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-16.6	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

C₉H₃₆F^- + 10 Methane = C₁₀H₄₀F^-

By formula: C₉H₃₆F^- + 10CH₄ = C₁₀H₄₀F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.53	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-17.4	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = CH₄Cl^-

By formula: Cl^- + CH₄ = CH₄Cl^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	15.9	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-9.04	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = ( • Methane )

By formula: Co⁺ + CH₄ = (Co⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	82.8	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(530 K); M

Enthalpy of reaction

Δ_rH° (kJ/mol)	Method	Reference	Comment
90.0 (+6.7,-0.)	CID	Haynes and Armentrout, 1996	gas phase; guided ion beam CID; M
90.0 (+5.9,-0.)	CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M
94. (+2.,-0.)	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(530 K); M

( • Methane ) + Methane = ( • 2 Methane )

By formula: (Co⁺ • CH₄) + CH₄ = (Co⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	109.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(500 K); M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
95.8 (+5.0,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M
104. (+4.2,-0.)		SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(500 K); M

( • 2 Methane ) + Methane = ( • 3 Methane )

By formula: (Co⁺ • 2CH₄) + CH₄ = (Co⁺ • 3CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	46.	kJ/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	84.	J/mol*K	N/A	Kemper, Bushnell, et al., 1993	gas phase; Entropy change calculated or estimated; M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
41. (+5.0,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

Free energy of reaction

Δ_rG° (kJ/mol)	T (K)	Method	Reference	Comment
3.	477.	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Entropy change calculated or estimated; M

( • 3 Methane ) + Methane = ( • 4 Methane )

By formula: (Co⁺ • 3CH₄) + CH₄ = (Co⁺ • 4CH₄)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
67.8 (+5.9,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

( • ) + Methane = ( • Methane • )

By formula: (Co⁺ • C₂H₆) + CH₄ = (Co⁺ • CH₄ • C₂H₆)

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	110.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(490 K); M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
102. (+4.6,-0.)		SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(490 K); M

( • ) + Methane = ( • Methane • )

By formula: (Co⁺ • H₂O) + CH₄ = (Co⁺ • CH₄ • H₂O)

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	113.	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(525 K); M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
108. (+3.,-0.)		SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(525 K); M

( • ) + Methane = ( • Methane • )

By formula: (Co⁺ • H₂) + CH₄ = (Co⁺ • CH₄ • H₂)

Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	91.2	J/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; switching reaction(Co+)2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993, 2; M

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
94.6 (+5.0,-0.)		SIDT	Kemper, Bushnell, et al., 1993	gas phase; switching reaction(Co+)2H2, Δ_rS(440 K); Kemper, Bushnell, et al., 1993, 2; M

+ Methane = CH₄F^-

By formula: F^- + CH₄ = CH₄F^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	28.0	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	6.82	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = ( • Methane )

By formula: Fe⁺ + CH₄ = (Fe⁺ • CH₄)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
57. (+3.,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

( • Methane ) + Methane = ( • 2 Methane )

By formula: (Fe⁺ • CH₄) + CH₄ = (Fe⁺ • 2CH₄)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
97.1 (+4.2,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

( • 2 Methane ) + Methane = ( • 3 Methane )

By formula: (Fe⁺ • 2CH₄) + CH₄ = (Fe⁺ • 3CH₄)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
99.2 (+5.9,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

( • 3 Methane ) + Methane = ( • 4 Methane )

By formula: (Fe⁺ • 3CH₄) + CH₄ = (Fe⁺ • 4CH₄)

Enthalpy of reaction

Δ_rH° (kJ/mol)	T (K)	Method	Reference	Comment
74.1 (+5.9,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

+ Methane = ( • Methane )

By formula: H₃O⁺ + CH₄ = (H₃O⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	33.	kJ/mol	HPMS	Bennet and Field, 1972, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	85.4	J/mol*K	HPMS	Bennet and Field, 1972, 2	gas phase; M

( • Methane ) + Methane = ( • 2 Methane )

By formula: (H₃O⁺ • CH₄) + CH₄ = (H₃O⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	14.	kJ/mol	HPMS	Bennet and Field, 1972, 2	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	34.	J/mol*K	HPMS	Bennet and Field, 1972, 2	gas phase; Entropy change is questionable; M

H₃S⁺ + Methane = (H₃S⁺ • Methane )

By formula: H₃S⁺ + CH₄ = (H₃S⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	16.	kJ/mol	HPMS	Bennet and Field, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	75.7	J/mol*K	HPMS	Bennet and Field, 1972	gas phase; M

+ Methane = ( • Methane )

By formula: H₄N⁺ + CH₄ = (H₄N⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	15.	kJ/mol	HPMS	Bennet and Field, 1972	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	64.9	J/mol*K	HPMS	Bennet and Field, 1972	gas phase; Entropy change is questionable; M

+ Methane = CH₄I^-

By formula: I^- + CH₄ = CH₄I^-

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	10.9	kJ/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-11.6	kJ/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = ( • Methane )

By formula: Mg⁺ + CH₄ = (Mg⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	28. ± 6.7	kJ/mol	CIDT	Andersen, Muntean, et al., 2000	RCD

( • Methane ) + Methane = ( • 2 Methane )

By formula: (Mg⁺ • CH₄) + CH₄ = (Mg⁺ • 2CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	15. ± 6.7	kJ/mol	CIDT	Andersen, Muntean, et al., 2000	RCD

+ Methane = ( • Methane )

By formula: Na⁺ + CH₄ = (Na⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	30.	kJ/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	59.0	J/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Ion clustering data, Notes

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Manion, 2002
Manion, J.A., Evaluated Enthalpies of Formation of the Stable Closed Shell C1 and C2 Chlorinated Hydrocarbons, J. Phys. Chem. Ref. Data, 2002, 31, 1, 123-172, https://doi.org/10.1063/1.1420703 . [all data]

Gurvich, Veyts, et al., 1991
Thermodynamic Properties of Individual Substances, 4th edition, Volume 2, Gurvich, L.V.; Veyts, I.V.; Alcock, C.B.;, ed(s)., Hemisphere, New York, 1991. [all data]

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 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]

Roth and Banse, 1932
Roth, W.A.; Banse, H., Die verbrennungs- und bildungswarme von kohlenoxyd und methan, Arch. Eisenhutten., 1932, 6, 43-46. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Rossini, 1931
Rossini, F.D., The heats of combustion of methane and carbon monoxide, J. Res. NBS, 1931, 6, 37-49. [all data]

Colwell J.H., 1963
Colwell J.H., Thermodynamic properties of CH4 and CD4. Interpretation of the properties of solid, J. Chem. Phys., 1963, 39, 635-653. [all data]

Vogt G.J., 1976
Vogt G.J., Entropy and heat capacity of methane; spin-species conversion, J. Chem. Thermodyn., 1976, 8, 1011-1031. [all data]

Friend D.G., 1989
Friend D.G., Thermophysical properties of methane, J. Phys. Chem. Ref. Data, 1989, 18, 583-638. [all data]

Gurvich, Veyts, et al., 1989
Gurvich, L.V.; Veyts, I.V.; Alcock, C.B., Thermodynamic Properties of Individual Substances, 4th ed.; Vols. 1 and 2, Hemisphere, New York, 1989. [all data]

Giauque W.F., 1931
Giauque W.F., The entropies of methane and ammonia, Phys. Rev., 1931, 38, 196-197. [all data]

East A.L.L., 1997
East A.L.L., Ab initio statistical thermodynamical models for the computation of third-law entropies, J. Chem. Phys., 1997, 106, 6655-6674. [all data]

Halford J.O., 1957
Halford J.O., Standard heat capacities of gaseous methanol, ethanol, methane and ethane at 279 K by thermal conductivity, J. Phys. Chem., 1957, 61, 1536-1539. [all data]

McDowell R.S., 1963
McDowell R.S., Thermodynamic functions of methane, J. Chem. Eng. Data, 1963, 8, 547-548. [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Berkowitz, Greene, et al., 1987
Berkowitz, J.; Greene, J.P.; Cho, H.; Ruscic, B., The ionization potentials of CH₄ and CD₄, J. Chem. Phys., 1987, 86, 674. [all data]

Chatham, Hils, et al., 1984
Chatham, H.; Hils, D.; Robertson, R.; Gallagher, A., Total and partial electron collisional ionization cross sections for CH₄, C₂H₆, SiH₄, and Si₂H₆, J. Chem. Phys., 1984, 81, 1770. [all data]

Plessis, Marmet, et al., 1983
Plessis, P.; Marmet, P.; Dutil, R., Ionization and appearance potentials of CH₄ by electron impact, J. Phys. B:, 1983, 16, 1283. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P., Valence ionization enrgies of hydrocarbons, Helv. Chim. Acta, 1977, 60, 2213. [all data]

Selim and El-Kholy, 1975
Selim, E.T.M.; El-Kholy, S.B., Mass spectrometric ionization and dissociation of methane, Indian J. Pure Appl. Phys., 1975, 13, 233. [all data]

Debies and Rabalais, 1975
Debies, T.P.; Rabalais, J.W., Calculated photoionization cross-sections and angular distributions for the isoelectronic series Ne, HF, H₂O, NH₃, and CH₄, J. Am. Chem. Soc., 1975, 97, 487. [all data]

Rabalais, Debies, et al., 1974
Rabalais, J.W.; Debies, T.P.; Berkosky, J.L.; Huang, J.-T.J.; Ellison, F.O., Calculated photoionization cross sections relative experimental photoionization intensities for a selection of small molecules, J. Chem. Phys., 1974, 61, 516. [all data]

Morrison and Traeger, 1973
Morrison, J.D.; Traeger, J.C., Ionization and dissociation by electron impact. III. CH₄ and SiH₄, Int. J. Mass Spectrom. Ion Phys., 1973, 11, 289. [all data]

Potts and Price, 1972
Potts, A.W.; Price, W.C., The photoelectron spectra of methane, silane germane and stannane, Proc. R. Soc. London A:, 1972, 165. [all data]

Finney and Harrison, 1972
Finney, C.D.; Harrison, A.G., A third-derivative method for determining electron-impact onset potentials, Int. J. Mass Spectrom. Ion Phys., 1972, 9, 221. [all data]

Bergmark, Rabalais, et al., 1972
Bergmark, T.; Rabalais, J.W.; Werme, L.O.; Karlsson, L.; Siegbahn, K., High-resolution electron spectra of methane, thiophene, 2-bromothiphene, and 3-bromothiophene in Electron Spectroscopy, ed. D.A. Shirley (North-Holland Pub. Co., Amsterdam), 1972. [all data]

Rabalais, Bergmark, et al., 1971
Rabalais, J.W.; Bergmark, T.; Werme, L.O.; Karlsson, L.; Siegbahn, K., The Jahn-Teller effect in the electron spectrum of methane, Phys. Scr., 1971, 3, 13. [all data]

Chupka and Berkowitz, 1971
Chupka, W.A.; Berkowitz, J., Photoionization of methane: ionization potential and proton affinity of CH₄, J. Chem. Phys., 1971, 54, 4256. [all data]

Pullen, Carlson, et al., 1970
Pullen, B.P.; Carlson, T.A.; Moddeman, W.E.; Schweitzer, G.K.; Bull, W.E., Photoelectron spectra of methane, silane, germane, methyl fluoride, difluoromethane, and trifluoromethane, J. Chem. Phys., 1970, 53, 768. [all data]

Brundle, Robin, et al., 1970
Brundle, C.R.; Robin, M.B.; Basch, H., Electronic energies and electronic structures of the fluoromethanes, J. Chem. Phys., 1970, 53, 2196. [all data]

Lossing and Semeluk, 1969
Lossing, F.P.; Semeluk, G.P., Threshold ionization efficiency curves for monoenergetic electron impact on H₂, D₂, CH₄ and CD₄, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 408. [all data]

Williams and Hamill, 1968
Williams, J.M.; Hamill, W.H., Ionization potentials of molecules and free radicals and appearance potentials by electron impact in the mass spectrometer, J. Chem. Phys., 1968, 49, 4467. [all data]

Villarejo, Stockbauer, et al., 1968
Villarejo, D.; Stockbauer, R.; Inghram, M.G., Measurement of threshold electrons in the photoionization of small molecules, Bull. Am. Phys. Soc., 1968, 13, 39. [all data]

Cermak, 1968
Cermak, V., Penning ionization electron spectroscopy. I. Determination of ionization potentials of polyatomic molecules, Collection Czech. Chem. Commun., 1968, 33, 2739. [all data]

Baker, Baker, et al., 1968
Baker, A.D.; Baker, C.; Brundle, C.R.; Turner, D.W., The electronic structures of methane, ethane, ethylene and formaldehyde studied by high-resolution molecular photoelectron spectroscopy, Intern. J. Mass Spectrom. Ion Phys., 1968, 1, 285. [all data]

Brehm, 1966
Brehm, B., Massenspektrometrische Untersuchung der Photoionisation von Molekulen, Z. Naturforsch., 1966, 21a, 196. [all data]

Nicholson, 1965
Nicholson, A.J.C., Photoionization-efficiency curves. II. False and genuine structure, J. Chem. Phys., 1965, 43, 1171. [all data]

Dibeler, Krauss, et al., 1965
Dibeler, V.H.; Krauss, M.; Reese, R.M.; Harllee, F.N., Mass-spectrometric study of photoionization. III. Methane and methane-d₄, J. Chem. Phys., 1965, 42, 3791. [all data]

Melton and Hamill, 1964
Melton, C.E.; Hamill, W.H., Appearance potentials by the retarding potential-difference method for secondary ions produced by excited-neutral, excited ion-neutral, and ion-neutral reactions, J. Chem. Phys., 1964, 41, 1469. [all data]

Bieri and Asbrink, 1980
Bieri, G.; Asbrink, L., 30.4-nm He(II) photoelectron spectra of organic molecules, J. Electron Spectrosc. Relat. Phenom., 1980, 20, 149. [all data]

Harshbarger, Robin, et al., 1973
Harshbarger, W.R.; Robin, M.B.; Lassettre, E.N., The electron impact spectra of the fluoromethanes, J. Electron Spectrosc. Relat. Phenom., 1973, 1, 319. [all data]

McCulloh and Dibeler, 1976
McCulloh, K.E.; Dibeler, V.H., Enthalpy of formation of methyl and methylene radicals of photoionization studies of methane and ketene, J. Chem. Phys., 1976, 64, 4445. [all data]

Chupka, 1968
Chupka, W.A., Mass-spectrometric study of the photoionization of methane, J. Chem. Phys., 1968, 48, 2337. [all data]

Stockbauer, 1977
Stockbauer, R., A threshold photoelectron-photoion coincidence mass spectrometer for measureing ion kinetic energy release on fragmentation, Int. J. Mass Spectrom. Ion Processes, 1977, 25, 89. [all data]

Lossing and Semeluk, 1970
Lossing, F.P.; Semeluk, G.P., Free radicals by mass spectrometry. XLII.Ionization potentials and ionic heats of formation for C₁-C₄ alkyl radicals, Can. J. Chem., 1970, 48, 955. [all data]

Locht, Olivier, et al., 1979
Locht, R.; Olivier, J.L.; Momigny, J., Dissociative autoionization as a mechanism for the proton formation from methane and methane-d₄ by low energy electron impact, Chem. Phys., 1979, 43, 425. [all data]

Appell and Kubach, 1971
Appell, J.; Kubach, C., On the formation of energetic protons by electron impact on methane, Chem. Phys. Lett., 1971, 11, 486. [all data]

Ellison, Engelking, et al., 1978
Ellison, G.B.; Engelking, P.C.; Lineberger, W.C., An experimental determination of the geometry and electron affinity of CH₃, J. Am. Chem. Soc., 1978, 100, 2556. [all data]

Graul and Squires, 1990
Graul, S.T.; Squires, R.R., Gas-Phase Acidities Derived from Threshold Energies for Activated Reactions, J. Am. Chem. Soc., 1990, 112, 7, 2517, https://doi.org/10.1021/ja00163a007 . [all data]

Bohme, Lee-Ruff, et al., 1972
Bohme, D.K.; Lee-Ruff, E.; Young, L.B., Acidity order of selected bronsted acids in the gas phase at 300K, J. Am. Chem. Soc., 1972, 94, 5153. [all data]

Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l . [all data]

Hiraoka, Mizuno, et al., 2001
Hiraoka, K.; Mizuno, T.; Iino, T.; Eguchi, D.; Yamabe, S., Characteristic changes of bond energies for gas-phase cluster ions of halide ions with methane and chloromethanes, J. Phys. Chem. A, 2001, 105, 20, 4887-4893, https://doi.org/10.1021/jp010143n . [all data]

Bennet and Field, 1972
Bennet, S.L.; Field, F.H., Reversible Reactions of Gaseous Ions. VI. The NH3 - CH4, H2S - CH4 and CF4 - CH4 Systems at Low Temperatures, J. Am. Chem. Soc., 1972, 94, 18, 6305, https://doi.org/10.1021/ja00773a009 . [all data]

Hiraoka and Mori, 1989
Hiraoka, K.; Mori, T., Gas - Phase Stability and Structure of Cluster Ions CH5+(CH4)n with n = 1 - 9, Chem. Phys. Lett., 1989, 161, 2, 111, https://doi.org/10.1016/0009-2614(89)85040-7 . [all data]

Hiraoka and Kebarle, 1975
Hiraoka, K.; Kebarle, P., Energetics, Stabilities and Possible Structures of CH5+(CH4)n Clusters from Gas Phase Study of Equilibria CH5+(CH4)n - 1 + CH4 = CH5+(CH4)n for n = 1 - 5, J. Am. Chem. Soc., 1975, 97, 15, 4179, https://doi.org/10.1021/ja00848a005 . [all data]

Field and Beggs, 1971
Field, F.H.; Beggs, D.P., Reversible Reactions of Gas Phase Ions. III. Studies with Methane at 0.1-1.0 Torr and 77-300 K, J. Am. Chem. Soc., 1971, 93, 7, 1585, https://doi.org/10.1021/ja00736a003 . [all data]

Hiraoka, Mori, et al., 1993
Hiraoka, K.; Mori, T.; Yamabe, S., The Gas-Phase Solvation of C2H5+, s-C3H7+ and s-C4H9+ with CH4. The Isomeric Structures of C2H5+ and C2H5+.CH4, Chem. Phys. Lett., 1993, 207, 2-3, 178, https://doi.org/10.1016/0009-2614(93)87011-Q . [all data]

Hiroka and Kebarle, 1975
Hiroka, K.; Kebarle, P., Information on the Proton Affinity and Protolysis of Propane from Measurement of the Ion Cluster Equilibrium: C2H5+ + CH4 = C3H9+, Can. J. Phys., 1975, 53, 970. [all data]

Hiraoka and Kebarle, 1976
Hiraoka, K.; Kebarle, P., Stabilities and Energetics of Pentacoordinated Carbonium Ions. The Isomeric C2H7+ Ions and Some Higher Analogues: C3H9+ and C4H11+, J. Am. Chem. Soc., 1976, 98, 20, 6119, https://doi.org/10.1021/ja00436a009 . [all data]

Hop and McMahon, 1991
Hop, C.E.C.A.; McMahon, T.B., Observation of a Weakly Bound Mn(CO)5+/CH4 Complex, J. Am. Chem. Soc., 1991, 113, 1, 355, https://doi.org/10.1021/ja00001a050 . [all data]

Kemper, Bushnell, et al., 1993
Kemper, P.R.; Bushnell, J.; Von Koppen, P.; Bowers, M.T., Binding Energies of Co+(H2/CH4/C2H6)1,2,3 Clusters, J. Phys. Chem., 1993, 97, 9, 1810, https://doi.org/10.1021/j100111a016 . [all data]

Haynes and Armentrout, 1996
Haynes, C.L.; Armentrout, P.B., Guided Ion Beam Determination of the Co+ - H2 Bond Dissociation energy, Chem Phys. Let., 1996, 249, 1-2, 64, https://doi.org/10.1016/0009-2614(95)01337-7 . [all data]

Armentrout and Kickel, 1994
Armentrout, P.B.; Kickel, B.L., Gas Phase Thermochemistry of Transition Metal Ligand Systems: Reassessment of Values and Periodic Trends, in Organometallic Ion Chemistry, B. S. Freiser, ed, 1994. [all data]

Kemper, Bushnell, et al., 1993, 2
Kemper, P.R.; Bushnell, J.; Von Helden, G.; Bowers, M.T., Co+(H2)n Clusters: Binding Energies and Molecular Parameters, J. Chem Phys., 1993, 97, 1, 52, https://doi.org/10.1021/j100103a012 . [all data]

Bennet and Field, 1972, 2
Bennet, S.L.; Field, F.H., Reversible Reactions of Gaseous Ions. V. The Methane - Water System at Low Temperatures, J. Am. Chem. Soc., 1972, 94, 15, 5188, https://doi.org/10.1021/ja00770a008 . [all data]

Andersen, Muntean, et al., 2000
Andersen, A.; Muntean, F.; Walter, D.; Rue, C.; Armentrout, P.B., Collision-Induced Dissociation and Theoretical Studies of Mg+ Complexes with CO, CO2, NH3, CH4, CH3OH, and C6H6, J. Phys. Chem. A, 2000, 104, 4, 692, https://doi.org/10.1021/jp993031t . [all data]

Castleman, Peterson, et al., 1983
Castleman, A.W.; Peterson, K.I.; Upschulte, B.L.; Schelling, F.J., Energetics and Structure of Na+ Cluster Ions, Int. J. Mass Spectrom. Ion Phys., 1983, 47, 203, https://doi.org/10.1016/0020-7381(83)87171-X . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Ion clustering data, References

Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
IE (evaluated)	Recommended ionization energy
S°_gas	Entropy of gas at standard conditions
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
T	Temperature
Δ_cH°_gas	Enthalpy of combustion of gas at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
Customer support for NIST Standard Reference Data products.