Toluene - Thermophysical Properties

Chemical, physical and thermal properties of toluene, also called methylbenzene, toluol and phenylmethane. Phase diagram included.

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Toluene, C₆H₅-CH₃, is a clear colorless liquid, highly flammable with a sweet, pungent aromatic odor.

Toluene is less dense than water and is slightly soluble in water. Hence it floats on water. Toluene vapor is heavier than air. Toluene may be toxic by inhalation, ingestion or skin contact.

Toluene is present in crude oils and is a product of oil-refining processes, thus it is used in aviation and automotive fuels. It is also used as a solvent, and to make other chemicals.

The phase diagram of toluene is shown below the table.

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

For full table with Imperial Units - rotate the screen!

Toluene - Thermophysical Properties
Property	Value	Unit	Value	Unit	Value	Unit	Value	Unit
Autoignition temperature	753	K	480	°C	896	°F
Boiling Point	383.8	K	110.6	°C	231.1	°F
Critical density	3.16	mol/dm³	291	kg/m³	0.565	slug/ft³	18.2	lb/ft³
Critical pressure	4.13	MPa=MN/m²	41.3	bar	40.7	atm	598	psi=lbf/in²
Critical temperature	592	K	319	°C	605	°F
Critical volume	316	cm³/mol	0.00343	m³/kg	1.77	ft³/slug	0.0550	ft³/lb
Density	9355	mol/m³	862.0	kg/m³	1.673	slug/ft³	53.81	lb/ft³
Flammable, gas and liquid	yes	highly
Flash point	277	K	4	°C	39	°F
Gas constant, individual, R	90.2	J/kg K	0.02507	Wh/(kg K)	539.6	[ft lbf/slug °R]	16.77	[ft lbf/lb °R]
Gibbs free energy of formation (gas)	122	kJ/mol	1324	kJ/kg	569	Btu/lb
Heat (enthalpy) of combustion (liquid)	-3920	kJ/mol	-42545	kJ/kg	-18291	Btu/lb
Heat (enthalpy) of formation (gas)	50	kJ/mol	543	kJ/kg	233	Btu/lb
Heat (enthalpy) of formation (liquid)	12	kJ/mol	130	kJ/kg	56	Btu/lb
Heat (enthalpy) of fusion at -139.3°F/-95.2°C	6.6	kJ/mol	72	kJ/kg	30.80	Btu/lb
Heat (enthalpy) of evaporation	38.0	kJ/mol	413	kJ/kg	177	Btu/lb
Specifc heat capacity, Cp (gas)	103.7	J/mol K	1.13	kJ/kg K	0.269	Btu/lb°F or cal/g K
Specific heat capacity, Cp (liquid)	157	J/mol K	1.70	kJ/kg K	0.407	Btu/lb°F or cal/g K
Specific heat capacity, Cv (liquid)	116.1	J/mol K	1.26	kJ/kg K	0.301	Btu/lb°F or cal/g K
Ionization potential	8.82	eV
log KOW (Octanol/Water Partition Coefficient)	2.73
Melting point	178.25	K	-94.9	°C	-138.8	°F
Molecular Weight	92.138	g/mol			0.20313	lb/mol
Solubility in water, at 25°C	0.526	mg/ml
Sound velocity	1305	m/s			4280	ft/s	2923	mi/h
Specific Gravity (gas) (relativ to air)	3.10
Specific Gravity (liquid) (relativ to water)	0.87
Specific Heat Ratio (liquid) - CP/CV	1.35
Specific Volume	0.0001069	m³/mol	0.00116	m³/kg	0.598	ft³/slug	0.0186	ft³/lb
Standard molar entropy, S° (gas)	321	J/mol K	3.48	kJ/kg K	0.83	Btu/lb °F
Standard molar entropy, S° (liquid)	220	J/mol K	2.39	kJ/kg K	0.57	Btu/lb °F
Surface tension	27.73	dynes/cm	0.02773	N/m
Thermal Conductivity	0.134	W/m°C			0.0774	Btu/hr ft °F
Triple point pressure	3.94E-08	MPa=MN/m²	3.94E-07	bar	3.89E-07	atm	5.71E-06	psi=lb_f/in²
Triple point temperature	178.0	K	-95.2	°C	-139.36	°F
Vapor (saturation) pressure	0.0038	MPa=MN/m²	28.4	mm Hg	0.037	atm	0.55	psi=lb_f/in²
Viscosity, dynamic (absolute)	0.560	cP			376.3	[lb_m /ft s*10^-6]	11.70	[lb_f s/ft² *10^-6]
Viscosity, kinematic	0.650	cSt			7.0	[ft²/s*10^-6]

See the following document for changes in toluene properties with changes in pressure and temperature:

Density and Specific Weight

Toluene is a liquid at standard conditions. However, if heated it becomes a gas, and when cooled it becomes a solid. The phase diagram for toluene shows the phase behavior with changes in temperature and pressure. The curve between the critical point and the triple point shows the toluene boiling point with changes in pressure. It also shows the saturation pressure with changes in temperature.

Toluene phase diagram

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.