Methane (data page)

This page provides supplementary chemical data on methane.

Material Safety Data Sheet

The handling of this chemical may incur notable safety precautions.^[1]

Structure and properties

Structure and properties
Index of refraction, nD	1.000444[2]
Dielectric constant, εr	1.6761 ε0 at −182 °C[3] 1.0008181 ε0 at −20 °C[4]
Bond strength	?
Bond length	0.10870 nm [5]
Bond angle	109.5°
Magnetic susceptibility	−17.4×10−6 cm3/mol[6]

Thermodynamic properties

Phase behavior
Triple point	90.67 K (−182.48 °C), 0.117 bar[7]
Critical point	190.6 K (−82.6 °C), 46.0 bar[7]
Std enthalpy change of fusion, ΔfusHo	1.1 kJ/mol
Std entropy change of fusion, ΔfusSo	12.1 J/(mol·K)
Std enthalpy change of vaporization, ΔvapHo	8.17 kJ/mol
Std entropy change of vaporization, ΔvapSo	? J/(mol·K)
Solid properties
Std enthalpy change of formation, ΔfHosolid	? kJ/mol
Standard molar entropy, Sosolid	? J/(mol K)
Heat capacity, cp	? J/(mol K)
Liquid properties
Std enthalpy change of formation, ΔfHoliquid	? kJ/mol
Standard molar entropy, Soliquid	? J/(mol K)
Heat capacity, cp	? J/(mol K)
Gas properties
Std enthalpy change of formation, ΔfHogas	−74.6 kJ/mol[8]
Standard molar entropy, Sogas	186.3 J/(mol K)[8]
Enthalpy of combustion ΔcHo	−802 kJ/mol[9]
Heat capacity, cp	35.7 J/(mol K)[8]
van der Waals' constants[10]	a = 228.29 L2 kPa/mol2 b = 0.04278 L/mol

Vapor pressure of liquid

P (mm Hg)		1	10	40	100	400	760	1520	3800	7600	15200	30400	45600
T (°C)		−205.9(s)	−195.5(s)	−187.7(s)	−181.4	−168.8	−161.5	−152.3	−138.3	−124.8	−108.5	−86.3	—

Table data obtained from CRC Handbook of Chemistry and Physics 44th ed. Annotation "(s)" indicates equilibrium temperature of vapor over solid. Otherwise temperature is equilibrium of vapor over liquid. Note that these are all negative temperature values.

Methane vapor pressure vs. temperature. Uses formula ${\displaystyle \log _{10}P_{\text{mm Hg}}=6.61184-{\frac {389.93}{266.00+T_{^{\circ }{\text{C}}}}}}$ given in Lange's Handbook of Chemistry, 10th ed. Note that formula loses accuracy near T_crit = −82.6 °C

Spectral data

Methane infrared spectrum

UV-Vis
λmax	? nm
Extinction coefficient, ε	?
IR
Major absorption bands	3019, 2917, 1534, 1306 cm−1[11]
NMR
Proton NMR
Carbon-13 NMR	−2.3 ppm[12]
Other NMR data
MS
Masses of main fragments

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• Except where noted otherwise, data relate to Standard temperature and pressure.
• Reliability of data general note.