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:
- Reaction thermochemistry data: reactions 1 to 50, reactions 51 to 100, reactions 101 to 112
- Henry's Law data
- Mass spectrum (electron ionization)
- Fluid Properties
Data at other public NIST sites:
Options:
- Switch to SI 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, Phase change data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Vibrational and/or electronic energy levels, 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	-17.89	kcal/mol	Review	Chase, 1998	Data last reviewed in March, 1961
Δ_fH°_gas	-17.8 ± 0.07	kcal/mol	Review	Manion, 2002	adopted recommendation of Gurvich, Veyts, et al., 1991; DRB
Δ_fH°_gas	-17.8 ± 0.1	kcal/mol	Ccb	Pittam and Pilcher, 1972	ALS
Δ_fH°_gas	-17.889 ± 0.075	kcal/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; ALS
Δ_fH°_gas	-17.54 ± 0.26	kcal/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -17.97 kcal/mol; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-212.88 ± 0.09	kcal/mol	Ccb	Pittam and Pilcher, 1972	Corresponding Δ_fHº_gas = -17.80 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-212.798 ± 0.072	kcal/mol	Ccb	Prosen and Rossini, 1945	Hf derived from Heat of Hydrogenation; Corresponding Δ_fHº_gas = -17.883 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-213.14 ± 0.26	kcal/mol	Ccb	Roth and Banse, 1932	Reanalyzed by Cox and Pilcher, 1970, Original value = -212.07 ± 0.25 kcal/mol; Corresponding Δ_fHº_gas = -17.54 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-212.753 ± 0.072	kcal/mol	Cm	Rossini, 1931	Corresponding Δ_fHº_gas = -17.928 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_gas	45.09 ± 0.10	cal/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}	44.515	cal/mol*K	Review	Chase, 1998	Data last reviewed in March, 1961

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
8.346 ± 0.060	279.	Halford J.O., 1957	GT

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
7.954	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
8.009	200.
8.530	298.15
8.547	300.
9.711	400.
11.14	500.
12.61	600.
14.01	700.
15.32	800.
16.52	900.
17.63	1000.
18.62	1100.
19.52	1200.
20.33	1300.
21.06	1400.
21.72	1500.
22.31	1600.
22.84	1700.
23.33	1800.
23.78	1900.
24.197	2000.
24.577	2100.
24.931	2200.
25.263	2300.
25.574	2400.
25.868	2500.
26.145	2600.
26.410	2700.
26.663	2800.
26.905	2900.
27.139	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 (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/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	-0.168028	20.50960
B	25.92670	2.692321
C	-10.16290	-0.505293
D	1.401240	0.033028
E	0.162181	-6.315060
F	-18.36610	-36.69520
G	37.93411	53.63631
H	-17.89510	-17.89510
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in March, 1961	Data last reviewed in March, 1961

Phase change data

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Vibrational and/or electronic energy levels, References, Notes

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
DH - Eugene S. Domalski and Elizabeth D. Hearing
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_boil	111. ± 2.	K	AVG	N/A	Average of 13 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_fus	85.7	K	N/A	Streng, 1971	Uncertainty assigned by TRC = 0.2 K; TRC
T_fus	90.6	K	N/A	Van't Zelfde, Omar, et al., 1968	Uncertainty assigned by TRC = 0.3 K; TRC
T_fus	91.2	K	N/A	Timmermans, 1935	Uncertainty assigned by TRC = 2. K; TRC
T_fus	90.6	K	N/A	Clusius, 1929	Uncertainty assigned by TRC = 0.2 K; TRC
T_fus	90.5	K	N/A	Eucken and Karwat, 1924	Uncertainty assigned by TRC = 0.2 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_triple	90.67 ± 0.03	K	AVG	N/A	Average of 25 out of 32 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
P_triple	0.1154 ± 0.0006	atm	AVG	N/A	Average of 20 out of 23 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_c	190.6 ± 0.3	K	AVG	N/A	Average of 19 out of 23 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
P_c	45.5 ± 0.3	atm	AVG	N/A	Average of 16 out of 21 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
V_c	0.09860	l/mol	N/A	Ambrose and Tsonopoulos, 1995
V_c	0.09852	l/mol	N/A	Younglove and Ely, 1987	TRC
V_c	0.100	l/mol	N/A	Terry, Lynch, et al., 1969	Uncertainty assigned by TRC = 0.001 l/mol; TRC
Quantity	Value	Units	Method	Reference	Comment
ρ_c	10.1 ± 0.2	mol/l	AVG	N/A	Average of 16 out of 17 values; Individual data points

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
2.036	99.54	N/A	Vogt and Pitzer, 1976	P = 2.81 kPa Data from Frank and Clusius, 1937 and 39FRA/CLU.; DH
2.1	101.	N/A	Stock, Henning, et al., 2006	Based on data from 92. to 110. K. See also Boublik, Fried, et al., 1984.; AC
2.1	105.	A	Stephenson and Malanowski, 1987	Based on data from 90. to 120. K.; AC
2.0	134.	A	Stephenson and Malanowski, 1987	Based on data from 115. to 149. K.; AC
2.1	174.	A	Stephenson and Malanowski, 1987	Based on data from 148. to 189. K.; AC
1.95	111.7	N/A	Majer and Svoboda, 1985
2.1	112.	N/A	Ott, Goates, et al., 1972	Based on data from 91. to 127. K. See also Boublik, Fried, et al., 1984.; AC
2.0	175.	N/A	Ott, Goates, et al., 1972	Based on data from 91. to 190. K.; AC
1.9	137.	N/A	Reid, 1972	AC
2.1	175.	N/A	Ambrose, Counsell, et al., 1970	Based on data from 100. to 190. K.; AC
2.0	112.	C	Hestermans and White, 1961	AC
1.8	130.	C	Hestermans and White, 1961	AC
1.4	160.	C	Hestermans and White, 1961	AC
0.96	180.	C	Hestermans and White, 1961	AC
2.0	149.	N/A	Hestermans and White, 1961	Based on data from 109. to 189. K.; AC
2.0 ± 0.02	99.	N/A	Frank and Clusius, 1939	AC

Enthalpy of vaporization

Δ_vapH = A exp(-αT_r) (1 − T_r)^β
Δ_vapH = Enthalpy of vaporization (at saturation pressure) (kcal/mol)
T_r = reduced temperature (T / T_c)

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

Temperature (K)	112. to 180.
A (kcal/mol)	2.416
α	-0.22
β	0.388
T_c (K)	190.6
Reference	Majer and Svoboda, 1985

Entropy of vaporization

Δ_vapS (cal/mol*K)	Temperature (K)	Reference	Comment
20.45	99.54	Vogt and Pitzer, 1976	P; DH

Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
P = vapor pressure (atm)
T = temperature (K)

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

Temperature (K)	A	B	C	Reference	Comment
90.99 to 189.99	3.9838	443.028	-0.49	Prydz and Goodwin, 1972	Coefficents calculated by NIST from author's data.
96.89 to 110.19	1.99682	125.819	-48.823	Regnier, 1972	Coefficents calculated by NIST from author's data.
93.04 to 107.84	3.79664	403.106	-5.479	Cutler and Morrison, 1965	Coefficents calculated by NIST from author's data.
110.00 to 190.5	4.21490	516.689	11.223	Hestermans and White, 1961	Coefficents calculated by NIST from author's data.

Enthalpy of sublimation

Δ_subH (kcal/mol)	Temperature (K)	Method	Reference	Comment
2.3	72.	N/A	Stephenson and Malanowski, 1987	Based on data from 53. to 91. K.; AC
2.2	72.	N/A	Bondi, 1963	Based on data from 54. to 90. K. See also Armstrong, Brickwedde, et al., 1955.; AC
2.39	84.	N/A	Jones, 1960	Based on data from 79. to 89. K.; AC
2.3	63.	A,MS	Tickner and Lossing, 1951	Based on data from 48. to 78. K.; AC
2.30	77.	A	Stull, 1947	Based on data from 67. to 88. K.; AC

Enthalpy of phase transition

ΔH_trs (kcal/mol)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
0.02236	20.53	crystaline, II	crystaline, I	Vogt and Pitzer, 1976	Lambda transition.; DH
0.2245	90.67	crystaline, I	liquid	Vogt and Pitzer, 1976	DH

Entropy of phase transition

ΔS_trs (cal/mol*K)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
1.089	20.53	crystaline, II	crystaline, I	Vogt and Pitzer, 1976	Lambda; DH
2.476	90.67	crystaline, I	liquid	Vogt and Pitzer, 1976	DH

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, Ion clustering data, IR Spectrum, Vibrational and/or electronic energy levels, 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)	129.9	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	124.4	kcal/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°	416.74 ± 0.70	kcal/mol	D-EA	Ellison, Engelking, et al., 1978	gas phase; B
Δ_rH°	418.0 ± 3.5	kcal/mol	CIDT	Graul and Squires, 1990	gas phase; B
Δ_rH°	>404.18 ± 0.10	kcal/mol	G+TS	Bohme, Lee-Ruff, et al., 1972	gas phase; B
Δ_rH°	414.80	kcal/mol	N/A	Check, Faust, et al., 2001	gas phase; FeBr3; ; ΔS(EA)=9.3; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	408.66 ± 0.80	kcal/mol	H-TS	Ellison, Engelking, et al., 1978	gas phase; B
Δ_rG°	409.9 ± 3.6	kcal/mol	H-TS	Graul and Squires, 1990	gas phase; B
Δ_rG°	>396.10	kcal/mol	IMRB	Bohme, Lee-Ruff, et al., 1972	gas phase; B
Δ_rG°	407.30	kcal/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, Phase change data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, 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°	3.10	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.27	kcal/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°	4.6	kcal/mol	HPMS	Bennet and Field, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.8	cal/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°	3.50	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.06	kcal/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°	5.90	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-0.36	kcal/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°	6.9 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	7.4	kcal/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rH°	4.1	kcal/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.1	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	20.8	cal/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rS°	12.4	cal/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°	5.3 ± 0.3	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	5.9	kcal/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rH°	1.5	kcal/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.9	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	24.4	cal/mol*K	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Δ_rS°	7.2	cal/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°	3.1 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	4.1	kcal/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.4	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	26.1	cal/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°	3.0 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rH°	3.9	kcal/mol	PHPMS	Hiraoka and Kebarle, 1975	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	23.7	cal/mol*K	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Δ_rS°	26.6	cal/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°	2.8 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	24.8	cal/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°	2.7 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	25.3	cal/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°	2.7 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	26.5	cal/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°	2.0 ± 0.2	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.6	cal/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°	1.54	kcal/mol	PHPMS	Hiraoka and Mori, 1989	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/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°	5.50	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rH°	6.6	kcal/mol	PHPMS	Hiroka and Kebarle, 1975	gas phase; M
Δ_rH°	2.4	kcal/mol	HPMS	Field and Beggs, 1971	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.2	cal/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rS°	23.4	cal/mol*K	PHPMS	Hiroka and Kebarle, 1975	gas phase; M
Δ_rS°	8.6	cal/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°	2.37	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	16.1	cal/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°	2.28	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.9	cal/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°	2.26	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.4	cal/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°	2.22	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.9	cal/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°	2.21	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/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°	2.13	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.7	cal/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°	2.10	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.0	cal/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°	2.08	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.8	cal/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°	1.91	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/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°	5.50	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-1.36	kcal/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°	2.59	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rH°	3.4	kcal/mol	PHPMS	Hiraoka and Kebarle, 1976	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	17.4	cal/mol*K	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Δ_rS°	20.	cal/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°	2.45	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.0	cal/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°	2.26	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.4	cal/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°	2.20	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.0	cal/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°	2.20	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.9	cal/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°	2.19	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.0	cal/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°	2.16	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	21.8	cal/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°	1.98	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	22.	cal/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°	5.00	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.16	kcal/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°	2.48	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.5	cal/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°	2.39	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/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°	2.37	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.7	cal/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°	2.36	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.0	cal/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°	2.21	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.4	cal/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°	2.09	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.3	cal/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°	2.05	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	19.7	cal/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°	1.99	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.1	cal/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°	1.86	kcal/mol	PHPMS	Hiraoka, Mori, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/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°	4.50	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.95	kcal/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°	4.20	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.25	kcal/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°	7.2	kcal/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°	3.30	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.96	kcal/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°	2.90	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.66	kcal/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°	2.30	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-3.96	kcal/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°	1.80	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-4.16	kcal/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°	3.80	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.16	kcal/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°	19.8	cal/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(530 K); M

Enthalpy of reaction

Δ_rH° (kcal/mol)	Method	Reference	Comment
21.5 (+1.6,-0.)	CID	Haynes and Armentrout, 1996	gas phase; guided ion beam CID; M
21.5 (+1.4,-0.)	CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M
22.5 (+0.5,-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°	26.1	cal/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(500 K); M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
22.9 (+1.2,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M
24.8 (+1.0,-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°	11.	kcal/mol	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.	cal/mol*K	N/A	Kemper, Bushnell, et al., 1993	gas phase; Entropy change calculated or estimated; M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
9.8 (+1.2,-0.)		CID	Armentrout and Kickel, 1994	gas phase; guided ion beam CID; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
0.7	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° (kcal/mol)	T (K)	Method	Reference	Comment
16.2 (+1.4,-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°	26.4	cal/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(490 K); M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
24.4 (+1.1,-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°	27.0	cal/mol*K	SIDT	Kemper, Bushnell, et al., 1993	gas phase; Δ_rS(525 K); M

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
25.9 (+0.7,-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°	21.8	cal/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° (kcal/mol)	T (K)	Method	Reference	Comment
22.6 (+1.2,-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°	6.70	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1.63	kcal/mol	TDAs	Hiraoka, Mizuno, et al., 2001	gas phase; B

+ Methane = ( • Methane )

By formula: Fe⁺ + CH₄ = (Fe⁺ • CH₄)

Enthalpy of reaction

Δ_rH° (kcal/mol)	T (K)	Method	Reference	Comment
13.6 (+0.7,-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° (kcal/mol)	T (K)	Method	Reference	Comment
23.2 (+1.0,-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° (kcal/mol)	T (K)	Method	Reference	Comment
23.7 (+1.4,-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° (kcal/mol)	T (K)	Method	Reference	Comment
17.7 (+1.4,-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°	8.0	kcal/mol	HPMS	Bennet and Field, 1972, 2	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	20.4	cal/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°	3.4	kcal/mol	HPMS	Bennet and Field, 1972, 2	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	8.1	cal/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°	3.9	kcal/mol	HPMS	Bennet and Field, 1972	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	18.1	cal/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°	3.6	kcal/mol	HPMS	Bennet and Field, 1972	gas phase; Entropy change is questionable; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	15.5	cal/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°	2.60	kcal/mol	N/A	Hiraoka, Mizuno, et al., 2001	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	-2.77	kcal/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°	6.7 ± 1.6	kcal/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°	3.5 ± 1.6	kcal/mol	CIDT	Andersen, Muntean, et al., 2000	RCD

+ Methane = ( • Methane )

By formula: Na⁺ + CH₄ = (Na⁺ • CH₄)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	7.2	kcal/mol	HPMS	Castleman, Peterson, et al., 1983	gas phase; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	14.1	cal/mol*K	HPMS	Castleman, Peterson, et al., 1983	gas phase; M

IR Spectrum

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, Vibrational and/or electronic energy levels, References, Notes

Data compiled by: Coblentz Society, Inc.

GAS (150 mmHg DILUTED TO A TOTAL PRESSURE OF 600 mmHg WITH N2); DOW KBr FOREPRISM; DIGITIZED BY NIST FROM HARD COPY (FROM TWO SEGMENTS); 4 cm^-1 resolution

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Vibrational and/or electronic energy levels

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, References, Notes

Data compiled by: Takehiko Shimanouchi

Symmetry: T_d Symmetry Number σ = 12

Sym.	No	Approximate	Selected Freq.		Infrared		Raman		Comments

Species		type of mode	Value	Rating	Value	Phase	Value	Phase

a₁	1	Sym str	2917	A	ia		2917.0	gas
e	2	Deg deform	1534	A	1533 ia	gas	1533.6		Observed through Coriolis interaction with ν₄
f₂	3	Deg str	3019	A	3018.9	gas	3019.5
f₂	4	Deg deform	1306	C	1306.2	gas

Source: Shimanouchi, 1972

Notes

Inactive

0~1 cm^-1 uncertainty

3~6 cm^-1 uncertainty

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Vibrational and/or electronic energy levels, 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]

Streng, 1971
Streng, A.G., Miscibility and Compatibility of Some Liquid and Solidified Gases at Low Temperature, J. Chem. Eng. Data, 1971, 16, 357. [all data]

Van't Zelfde, Omar, et al., 1968
Van't Zelfde, P.; Omar, M.H.; LePair-Schroten, H.G.M.; Dokoupil, Z., Solid-liquid equilibrium diagram for the argon + methane system., Physica (Amsterdam), 1968, 38, 241-51. [all data]

Timmermans, 1935
Timmermans, J., Researches in Stoichiometry. I. The Heat of Fusion of Organic Compounds., Bull. Soc. Chim. Belg., 1935, 44, 17-40. [all data]

Clusius, 1929
Clusius, K., The specific heat of several condensed gases between 10deg. abs. and their triple point., Z. Phys. Chem., Abt. B, 1929, 3, 41. [all data]

Eucken and Karwat, 1924
Eucken, A.; Karwat, E., Determination of the heat content of several condensed gases, Z. Phys. Chem., Stoechiom. Verwandtschaftsl., 1924, 112, 467. [all data]

Ambrose and Tsonopoulos, 1995
Ambrose, D.; Tsonopoulos, C., Vapor-Liquid Critical Properties of Elements and Compounds. 2. Normal Alkenes, J. Chem. Eng. Data, 1995, 40, 531-546. [all data]

Younglove and Ely, 1987
Younglove, B.A.; Ely, J.F., Thermophysical Properties of Fluids II. Methane, Ethane, Propane, Isobutane, and Normal Butane, J. Phys. Chem. Ref. Data, 1987, 16, 577. [all data]

Terry, Lynch, et al., 1969
Terry, M.J.; Lynch, J.T.; Bunclark, M.; Mansell, K.R.; Staveley, L.A.K., The Densities of Liquid Argon, Krypton, Xenon, Oxygen, Nitrogen, Carbon Monoxide, Methane and Carbon Tetrafluoride Along the Orthobaric Liquid Curve, J. Chem. Thermodyn., 1969, 1, 413. [all data]

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

Frank and Clusius, 1937
Frank, A.; Clusius, K., The entropy of methane, Z. Physik. Chem., 1937, B36, 291-300. [all data]

Stock, Henning, et al., 2006
Stock, Alfred; Henning, Fritz; Kuß, Ernst, Dampfdrucktafeln für Temperaturbestimmungen zwischen + 25° und - 185°, Ber. dtsch. Chem. Ges. A/B, 2006, 54, 5, 1119-1129, https://doi.org/10.1002/cber.19210540531 . [all data]

Boublik, Fried, et al., 1984
Boublik, T.; Fried, V.; Hala, E., The Vapour Pressures of Pure Substances: Selected Values of the Temperature Dependence of the Vapour Pressures of Some Pure Substances in the Normal and Low Pressure Region, 2nd ed., Elsevier, New York, 1984, 972. [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Majer and Svoboda, 1985
Majer, V.; Svoboda, V., Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation, Blackwell Scientific Publications, Oxford, 1985, 300. [all data]

Ott, Goates, et al., 1972
Ott, J. Bevan; Goates, J. Rex; Lamb, John D., Solid-liquid phase equilibria in water + ethylene glycol, The Journal of Chemical Thermodynamics, 1972, 4, 1, 123-126, https://doi.org/10.1016/S0021-9614(72)80015-6 . [all data]

Reid, 1972
Reid, Robert C., Handbook on vapor pressure and heats of vaporization of hydrocarbons and related compounds, R. C. Wilhort and B. J. Zwolinski, Texas A Research Foundation. College Station, Texas(1971). 329 pages.$10.00, AIChE J., 1972, 18, 6, 1278-1278, https://doi.org/10.1002/aic.690180637 . [all data]

Ambrose, Counsell, et al., 1970
Ambrose, D.; Counsell, J.F.; Davenport, A.J., The use of Chebyshev polynomials for the representation of vapour pressures between the triple point and the critical point, The Journal of Chemical Thermodynamics, 1970, 2, 2, 283-294, https://doi.org/10.1016/0021-9614(70)90093-5 . [all data]

Hestermans and White, 1961
Hestermans, P.; White, David, THE VAPOR PRESSURE, HEAT OF VAPORIZATION AND HEAT CAPACITY OF METHANE FROM THE BOILING POINT TO THE CRITICAL TEMPERATURE, J. Phys. Chem., 1961, 65, 2, 362-365, https://doi.org/10.1021/j100820a044 . [all data]

Frank and Clusius, 1939
Frank, A.; Clusius, K., Z. Phys. Chem. Abt. B, 1939, 42, 395. [all data]

Prydz and Goodwin, 1972
Prydz, R.; Goodwin, R.D., Experimental Melting and Vapor Pressures of Methane, J. Chem. Thermodyn., 1972, 4, 1, 127-133, https://doi.org/10.1016/S0021-9614(72)80016-8 . [all data]

Regnier, 1972
Regnier, J., Tension de Vapeur de L'Ethane Entre 80 et 135 K, J. Chim. Phys., 1972, 69, 942-944. [all data]

Cutler and Morrison, 1965
Cutler, A.J.B.; Morrison, J.A., Excess Thermodynamic Functions for Liquid Mixtures of Methane+Propane, Trans. Faraday Soc., 1965, 61, 429-442, https://doi.org/10.1039/tf9656100429 . [all data]

Bondi, 1963
Bondi, A., Heat of Siblimation of Molecular Crystals: A Catalog of Molecular Structure Increments., J. Chem. Eng. Data, 1963, 8, 3, 371-381, https://doi.org/10.1021/je60018a027 . [all data]

Armstrong, Brickwedde, et al., 1955
Armstrong, George T.; Brickwedde, F.G.; Scott, R.B., Vapor pressures of the methanes, J. RES. NATL. BUR. STAN., 1955, 55, 1, 39, https://doi.org/10.6028/jres.055.005 . [all data]

Jones, 1960
Jones, A.H., Sublimation Pressure Data for Organic Compounds., J. Chem. Eng. Data, 1960, 5, 2, 196-200, https://doi.org/10.1021/je60006a019 . [all data]

Tickner and Lossing, 1951
Tickner, A.W.; Lossing, F.P., The Measurement of Low Vapor Pressures by Means of a Mass Spectrometer., J. Phys. Chem., 1951, 55, 5, 733-740, https://doi.org/10.1021/j150488a013 . [all data]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [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]

Shimanouchi, 1972
Shimanouchi, T., Tables of Molecular Vibrational Frequencies Consolidated Volume I, National Bureau of Standards, 1972, 1-160. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, Vibrational and/or electronic energy levels, References

Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
IE (evaluated)	Recommended ionization energy
P_c	Critical pressure
P_triple	Triple point pressure
S°_gas	Entropy of gas at standard conditions
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
T	Temperature
T_boil	Boiling point
T_c	Critical temperature
T_fus	Fusion (melting) point
T_triple	Triple point temperature
V_c	Critical volume
ΔH_trs	Enthalpy of phase transition
ΔS_trs	Entropy of phase transition
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
Δ_subH	Enthalpy of sublimation
Δ_vapH	Enthalpy of vaporization
Δ_vapS	Entropy of vaporization
ρ_c	Critical density

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.

Methane

Data at NIST subscription sites:

Gas phase thermochemistry data

Constant pressure heat capacity of gas

Constant pressure heat capacity of gas

Gas Phase Heat Capacity (Shomate Equation)

Phase change data

Enthalpy of vaporization

Enthalpy of vaporization

Entropy of vaporization

Antoine Equation Parameters

Enthalpy of sublimation

Enthalpy of phase transition

Entropy of phase transition

Gas phase ion energetics data

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

Ion clustering data

Clustering reactions

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Free energy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

Enthalpy of reaction

IR Spectrum

Vibrational and/or electronic energy levels

Symmetry: Td Symmetry Number σ = 12

Notes

References

Notes

Symmetry: T_d Symmetry Number σ = 12