Benzene (data page)

This page provides supplementary chemical data on benzene.

Material Safety Data Sheet

The handling of this chemical may incur notable safety precautions. It is highly recommended to seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source such as SIRI, and follow its directions. MSDS for benzene is available at AMOCO.

Structure and properties

Structure and properties
Refractive index, nD	1.5011 at 20 °C
Abbe number	?
Dielectric constant, εr	(2.274 – 0.0020ΔT) ε0 (ΔT = T – 25 °C)
Bond energy	?
Bond length	1.39 Å C-C[1]
Molecular geometry	120 °C–C–C 120° H–C–C
Magnetic susceptibility	?
Surface tension	28.88 dyn/cm at 25 °C
Viscosity[2]	0.7528 mPa·s at 10 °C 0.6999 mPa·s at 15 °C 0.6516 mPa·s at 20 °C 0.6076 mPa·s at 25 °C 0.5673 mPa·s at 35 °C 0.4965 mPa·s at 40 °C 0.4655 mPa·s at 45 °C 0.4370 mPa·s at 50 °C 0.4108 mPa·s at 55 °C 0.3867 mPa·s at 60 °C 0.3644 mPa·s at 65 °C 0.3439 mPa·s at 70 °C 0.3250 mPa·s at 75 °C 0.3075 mPa·s at 80 °C

Thermodynamic properties

Phase behavior
Triple point	278.5 K (5.4 °C), 4.83 kPa
Critical point	562 K (289 °C), 4.89 MPa
Std enthalpy change of fusion, ΔfusHo	9.9 kJ/mol at 5.42 °C
Std entropy change of fusion, ΔfusSo	35.5 J/(mol·K) at 5.42 °C
Std enthalpy change of vaporization, ΔvapHo	33.9 kJ/mol at 25 °C 30.77 kJ/mol at 80.1 °C
Std entropy change of vaporization, ΔvapSo	113.6 J/(mol·K) at 25 °C 87.1 J/(mol·K) at 80.1 °C
Solid properties
Std enthalpy change of formation, ΔfHosolid	? kJ/mol
Standard molar entropy, Sosolid	45.56 J/(mol K)
Heat capacity, cp	118.4 J/(mol K) at 0 °C
Liquid properties
Std enthalpy change of formation, ΔfHoliquid	+48.7 kJ/mol
Standard molar entropy, Soliquid	173.26 J/(mol K)
Enthalpy of combustion, ΔcHo	–3273 kJ/mol
Heat capacity,[2] cp	134.8 J/(mol K)
Gas properties
Std enthalpy change of formation, ΔfHogas	+82.93 kJ/mol
Standard molar entropy,[3] Sogas	269.01 J/(mol K)
Heat capacity,[2] cp	82.44 J/(mol K) at 25 °C
van der Waals' constants[4]	a = 1823.9 L2 kPa/mol2 b = 0.1154 liter per mole

Vapor pressure of liquid

P in mm Hg		1	10	40	100	400	760	1520	3800	7600	15200	30400	45600
T in °C		–36.7(s)	–11.5(s)	7.6	26.1	60.6	80.1	103.8	142.5	178.8	221.5	272.3	—

Table data obtained from CRC Handbook of Chemistry and Physics 44th ed. Note: (s) notation indicates equilibrium temperature of vapor over solid, otherwise value is equilibrium temperature of vapor over liquid.

log of Benzene vapor pressure. Uses formula: ${\displaystyle \scriptstyle \log _{e}P_{mmHg}=}$${\displaystyle \scriptstyle \log _{e}({\frac {760}{101.325}})-8.433613\log _{e}(T+273.15)-{\frac {6281.040}{T+273.15}}+71.10718+6.198413\times 10^{-06}(T+273.15)^{2}}$ obtained from CHERIC^[2] Note: yellow area is the region where the formula disagrees with tabulated data above.

Distillation data

Vapor-liquid Equilibrium for Benzene/Ethanol[5] P = 760 mm Hg BP Temp. °C  % by mole ethanol liquid vapor 70.8 8.6 26.5 69.8 11.2 28.2 69.6 12.0 30.8 69.1 15.8 33.5 68.5 20.0 36.8 67.7 30.8 41.0 67.7 44.2 44.6 68.1 60.4 50.5 69.6 77.0 59.0 70.4 81.5 62.8 70.9 84.1 66.5 72.7 89.8 74.4 73.8 92.4 78.2

Vapor-liquid Equilibrium for Benzene/Methanol[5] P = 760 mm Hg BP Temp. °C  % by mole methanol liquid vapor 70.67 2.6 26.7 66.44 5.0 37.1 62.87 8.8 45.7 60.20 16.4 52.6 58.64 33.3 55.9 58.02 54.9 59.5 58.10 69.9 63.3 58.47 78.2 66.5 59.90 89.8 76.0 62.71 97.3 90.7

Vapor-liquid Equilibrium for Benzene/Acetone[5] P = 101.325 kPa BP Temp. °C  % by mole benzene liquid vapor 57.34 11.7 7.4 57.48 12.8 8.1 57.75 15.1 9.5 59.21 26.7 16.6 59.24 27.0 16.7 60.01 32.7 20.2 60.71 37.3 23.1 61.05 39.8 24.7 61.91 45.0 27.9 62.82 50.2 31.7 63.39 53.4 33.9 63.79 55.4 35.3 64.22 57.2 37.0 64.99 61.3 39.9 67.88 73.0 51.2 70.21 80.7 60.1 72.23 86.1 67.9

Vapor-liquid Equilibrium for Benzene/n-Hexane[5] P = 760 mmHg BP Temp. °C  % by mole hexane liquid vapor 77.6 7.3 14.0 75.1 17.2 26.8 73.4 26.8 37.6 72.0 37.2 46.0 70.9 46.2 54.0 70.0 58.5 64.4 69.4 69.2 72.5 69.1 79.2 80.7 69.0 82.8 83.8 68.9 88.3 88.8 68.8 94.7 95.0 68.8 96.2 96.4

Spectral data

UV-Vis
Ionization potential	9.24 eV (74525.6 cm−1)
S1	4.75 eV (38311.3 cm−1)
S2	6.05 eV (48796.5 cm−1)
λmax	255 nm
Extinction coefficient, ε	?
IR
Major absorption bands[6]	(liquid film) Wave number transmittance 3091 cm−1 42% 3072 cm−1 49% 3036 cm−1 27% 1961 cm−1 77% 1815 cm−1 70% 1526 cm−1 81% 1479 cm−1 20% 1393 cm−1 84% 1176 cm−1 86% 1038 cm−1 49% 674 cm−1 4%
NMR
Proton NMR	(CDCl3, 300 MHz) δ 7.34 (s, 6H)
Carbon-13 NMR	(CDCl3, 25 MHz) δ 128.4
Other NMR data
MS
Masses of main fragments

Safety data

Material Safety Data Sheet for benzene:

Common synonyms	None
Physical properties	Form: colorless liquid
	Stability: Stable, but very flammable
	Melting point: 5.5 C
	Water solubility: negligible
	Specific gravity: 0.87
Principal hazards	*** Benzene is a carcinogen (cancer-causing agent).
	*** Very flammable. The pure material, and any solutions containing it, constitute a fire risk.
Safe handling	Benzene should NOT be used at all unless no safer alternatives are available.
	If benzene must be used in an experiment, it should be handled at all stages in a fume cupboard.
	Wear safety glasses and use protective gloves.
Emergency	Eye contact: Immediately flush the eye with plenty of water. Continue for at least ten minutes
	and call for immediate medical help.
	Skin contact: Wash off with soap and water. Remove any contaminated clothing. If the skin
	reddens or appears damaged, call for medical aid.
	If swallowed: Call for immediate medical help.
Disposal	It is dangerous to try to dispose of benzene by washing it down a sink, since it is toxic, will cause environmental damage
	and presents a fire risk. It is probable that trying to dispose of benzene in this way will also break local
	environmental rules. Instead, retain in a safe place in the laboratory (well away from any source of ignition)
	for disposal with other flammable, non-chlorinated solvents.
Protective equipment	Safety glasses. If gloves are worn, PVA, butyl rubber and viton are suitable materials.