Methane (data page)

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This page provides supplementary chemical data on methane.

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)11040100400760152038007600152003040045600
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 given in Lange's Handbook of Chemistry, 10th ed. Note that formula loses accuracy near Tcrit = −82.6 °C

Spectral data

References

Cited sources

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