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Pentane - Thermophysical Properties

Chemical, physical and thermal properties of pentane, also called n-pentane. Phase diagram included.

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Pentane, C5H12, is a clear colorless liquid with a petroleum-like odor. It belongs to the organic class alkanes, and is naturally present in crude oils and condensates. It is a component of some fuels and is employed as a specialty solvent in the laboratory.

The boling point 36°C/97°F, and the vapors are heavier than air. Both the liquid an the vapor are flammable.

The phase diagram of pentane is shown below the table.

Chemical, physical and thermal properties of pentane:
Values are given for liquid at 25oC /77oF / 298 K and 1 bara, if not other phase, temperature or pressure given.

For full table with Imperial Units - rotate the screen!

Property Value Unit Value Unit Value Unit Value Unit
Autoignition temperature 533 K 260 °C 500 °F
Boiling Point 309.2 K 36.06 °C 96.9 °F
Critical density 3.22 mol/dm3 232 kg/m3 0.450 slug/ft3 14.5 lb/ft3
Critical pressure 3.36 MPa=MN/m2 33.6 bar 33.2 atm 487 psi=lbf/in2
Critical temperature 469.8 K 196.7 °C 386.0 °F
Critical volume 311 cm3/mol 0.00431 m3/kg 2.22 ft3/slug 0.0690 ft3/lb
Density 8606 mol/m3 620.9 kg/m3 1.205 slug/ft3 38.76 lb/ft3
Flammable, gas and liquid yes
Flash point 224 K -49 °C -56 °F
Gas constant, individual, R 115.2 J/kg K 0.03201 Wh/(kg K) 689.1 [ft lbf/slug °R] 21.42 [ft lbf/lb °R]
Gibbs free energy of formation (gas) -8 kJ/mol -111 kJ/kg -48 Btu/lb
Heat (enthalpy) of combustion (gas) -3535 kJ/mol -48996 kJ/kg -21.1 Btu/lb
Heat (enthalpy) of combustion (liquid) -3509 kJ/mol -48636 kJ/kg -20.9 Btu/lb
Heat (enthalpy) of formation (gas) -147.0 kJ/mol -2037 kJ/kg -876 Btu/lb
Heat (enthalpy) of formation (liquid) -173 kJ/mol -2398 kJ/kg -1031 Btu/lb
Heat (enthalpy) of fusion at -202 °F/-130°C 8.4 kJ/mol 116 kJ/kg 50.05 Btu/lb
Heat (enthalpy) of sublimation, at -202°F/-130°C 42 kJ/mol 582 kJ/kg 250 Btu/lb
Heat (enthalpy) of evaporation 26.4 kJ/mol 366 kJ/kg 157 Btu/lb
Heat capacity, Cp (gas) 120.0 J/mol K 1.66 kJ/kg K 0.397 Btu/lb°F or cal/g K
Specific heat, Cp (liquid) 168.0 J/mol K 2.33 kJ/kg K 0.556 Btu/lb°F or cal/g K
Specific heat, Cv (liquid) 125.0 J/mol K 1.73 kJ/kg K 0.414 Btu/lb°F or cal/g K
Ionization potential 10.34 eV
log KOW (Octanol/Water Partition Coefficient) 3.39
Melting point 143.48 K -129.7 °C -201.4 °F
Molecular Weight 72.149 g/mol 0.15906 lb/mol
Solubility in water, at 25°C 0.038 mg/ml
Sound velocity 1012 m/s 3319 ft/s 2267 mi/h
Specific Gravity (gas) (relativ to air) 2.48
Specific Gravity (liquid) (relativ to water) 0.63
Specific Heat Ratio (gas) - CP/CV 1.09
Specific Heat Ratio (liquid) - CP/CV 1.34
Specific Volume 0.0001162 m3/mol 0.0016106 m3/kg 0.8300514 ft3/slug 0.0257988 ft3/lb
Standard molar entropy, S° (gas) 348 J/mol K 4.82 kJ/kg K 1.15 Btu/lb °F
Standard molar entropy, S° (liquid) 263 J/mol K 3.65 kJ/kg K 0.87 Btu/lb °F
Surface tension 16.0 dynes/cm 0.016 N/m
Thermal Conductivity 0.111 W/m°C 0.064135 Btu/hr ft °F
Triple point pressure 7.63*10-8 MPa=MN/m2 7.63*10-7 bar 7.53*10-7 atm 1.11*10-5 psi=lbf/in2
Triple point temperature 143.5 K -129.7 °C -201.46 °F
Vapor (saturation) pressure 0.0685 MPa=MN/m2 514.0 mm Hg 0.6762 atm 9.94 psi=lbf/in2
Viscosity, dynamic (absolute) 0.2224 cP 149.4 [lbm /ft s*10-6] 4.64 [lbf s/ft2 *10-6]
Viscosity, kinematic 0.358 cSt 3.9 [ft2/s*10-6]

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Density of pentane with varying temperature and pressure

See also more about atmospheric pressure, and STP - Standard Temperature and Pressure & NTP - Normal Temperature and Pressure,
as well as Thermophysical properties of: Acetone, Acetylene, Air, Ammonia, Argon, Benzene, Butane, Carbon dioxide, Carbon monoxide, Ethane, Ethanol, Ethylene, Helium, Hydrogen, Hydrogen sulfide, Methane, Methanol, Nitrogen, Oxygen, Propane, Toluene, Water and Heavy water, D2O.

Pentane is a liquid at standard conditions. However, if heated above 36°C/97°F it becomes a gas, and when cooled it becomes a solid. The phase diagram for pentane shows the phase behavior with changes in temperature and pressure. The curve between the critical point and the triple point shows the pentane boiling point with changes in pressure. It also shows the saturation pressure with changes in temperature.

At the critical point there is no change of state when pressure is increased or if heat is added.

The triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.

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