Benzene (data page) explained

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

Refractive index, n_D

1.5011 at 20 °C

Abbe number

Dielectric constant, ε_r

(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, Δ_fusH^o	9.9 kJ/mol at 5.42 °C
Std entropy change of fusion, Δ_fusS^o	35.5 J/(mol·K) at 5.42 °C
Std enthalpy change of vaporization, Δ_vapH^o	33.9 kJ/mol at 25 °C 30.77 kJ/mol at 80.1 °C
Std entropy change of vaporization, Δ_vapS^o	113.6 J/(mol·K) at 25 °C 87.1 J/(mol·K) at 80.1 °C
	Solid properties
Std enthalpy change of formation, Δ_fH^o_solid	? kJ/mol
Standard molar entropy, S^o_solid	45.56 J/(mol K)
Heat capacity, c_p	118.4 J/(mol K) at 0 °C
	Liquid properties
Std enthalpy change of formation, Δ_fH^o_liquid	+48.7 kJ/mol
Standard molar entropy, S^o_liquid	173.26 J/(mol K)
Enthalpy of combustion, Δ_cH^o	–3273 kJ/mol
Heat capacity, c_p	134.8 J/(mol K)
	Gas properties
Std enthalpy change of formation, Δ_fH^o_gas	+82.93 kJ/mol
Standard molar entropy,^[3] S^o_gas	269.01 J/(mol K)
Heat capacity, c_p	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.

Distillation data

BP Temp. °C	% by mole ethanol
Vapor-liquid Equilibrium for Benzene/Ethanol^[5] P = 760 mm Hg
BP Temp. °C	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

BP Temp. °C	% by mole methanol
Vapor-liquid Equilibrium for Benzene/Methanol P = 760 mm Hg
BP Temp. °C	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

BP Temp. °C	% by mole benzene
Vapor-liquid Equilibrium for Benzene/Acetone P = 101.325 kPa
BP Temp. °C	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

BP Temp. °C	% by mole hexane
Vapor-liquid Equilibrium for Benzene/n-Hexane P = 760 mmHg
BP Temp. °C	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)

λ_max

255 nm

Extinction coefficient, ε

Major absorption bands^[6]

Wave number	transmittance
(liquid film)
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

(CDCl₃, 300 MHz) δ 7.34 (s, 6H)

(CDCl₃, 25 MHz) δ 128.4

Other NMR data

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.

References

Book: Brown. LeMay. Bursten. Chemistry: The Central Science. 2006. Pearson Education. Upper Saddle River, NJ. 0-13-109686-9. 1067. registration.
Web site: Pure Component Properties. Chemical Engineering Research Information Center. 12 May 2007. Queriable database.
Web site: ETP Entropy of Benzene. Queriable database. Dortmund Data Bank. 7 October 2011.
Lange's Handbook of Chemistry 10th ed, pp. 1522–1524
Web site: Binary Vapor-Liquid Equilibrium Data. Chemical Engineering Research Information Center. Queriable database. 12 May 2007.
Web site: Spectral Database for Organic Compounds . Advanced Industrial Science and Technology . Queriable database . 10 June 2007 . dead . https://web.archive.org/web/20060505120103/http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi . 5 May 2006 .