van der Waal's Constants for Real Gases
The van der Waal's equation of state for a real gas is:
(P + n2a / V2)(V- nb) = nRT
To convert 'a' into atm L2/mol2 multiply by 0.986 atm/bar
To convert 'a' into kPa L2/mol2 multiply by 100.0 kPa/bar 
Molecular Formula
Name
a
bar L2/mol2
b
L/mol
AlCl3
Aluminum trichloride
42.63
0.2450
NH3
Ammonia
4.225
0.03713
NH4Cl
Ammonium chloride
2.380
0.00734
Ar
Argon
1.355
0.03201
BCl3
Boron trichloride
15.60
0.1222
BF3
Boron trifluoride
3.98
0.05443
B2H6
Diborane
6.048
0.07437
Br2
Bromine
9.75
0.0591
ClFO2
Perchloryl fluoride
7.371
0.07130
ClF5
Chlorine pentafluoride
9.58
0.08204
ClH4P
Phosphonium chloride
4.111
0.04545
Cl2
Chlorine
6.343
0.05422
Cl3FSi
Trichlorofluorosilane
15.67
0.1273
F2
Fluorine
1.171
0.02896
GeCl4
Germanium tetrachloride
23.12
0.1489
F3N
Nitrogen trifluoride
3.58
0.05453
F3P
Phosphorus trifluoride
4.954
0.06510
F4N2
Tetrafluorohydrazine
7.426
0.08564
GeH4
Germane
5.743
0.06555
He
Helium
0.0346
0.0238
HBr
Hydrogen bromide
4.500
0.04415
HCl
Hydrogen chloride
3.700
0.04061
HCN
Hydrogen cyanide
11.29
0.08806
HF
Hydrogen fluoride
9.565
0.0739
HI
Hydrogen iodide
6.309
0.05303
H2
Hydrogen
0.2453
0.02651
H2O
Water
5.537
0.03049
H2S
Hydrogen sulphide
4.544
0.04339
H2Se
Hydrogen selenide
5.523
0.0479
Kr
Krypton
2.325
0.0396
SiH4
Silane
4.38
0.0579
SiCl4
Silicon tetrachloride
20.96
0.1470
SiF4
Silicon tetrafluoride
5.259
0.07236
TiCl4
Titanium(IV) chloride
25.47
0.1423
Hg
Mercury
5.193
0.01057
NO
Nitric oxide
1.46
0.0289
NO2
Nitrogen dioxide
5.36
0.0443
N2
Nitrogen
1.370
0.0387
N2O
Nitrous oxide
3.852
0.04435
N2H4
Hydrazine
8.46
0.0462
Ne
Neon
0.208
0.01672
O2
Oxygen
1.382
0.03186
O3
Ozone
3.570
0.0487
P
Phosphorus
53.6
0.157
PH3
Phosphine
4.696
0.05157
Rn
Radon
6.601
0.06239
SnCl4
Stannic chloride
27.25
0.1641
S
Sulphur
24.3
0.0660
SO2
Sulphur dioxide
6.865
0.05679
SF6
Sulphur hexafluoride
7.857
0.08786
Se
Selenium
33.4
0.0675
UF6
Uranium(VI) fluoride
16.01
0.1128
WF6
Tungsten(VI) fluoride
13.25
0.1063
Xe
Xenon
4.192
0.05156
XeF2
Xenon difluoride
12.46
0.07037
XeF4
Xenon tetrafluoride
15.52
0.09035
CClF3
Chlorotrifluoromethane
6.873
0.08110
CCl3F
Trichlorofluoromethane
14.68
0.1111
CCl4
Tetrachloromethane
20.01
0.1281
CF4
Tetrafluoromethane
4.040
0.06325
CO
Carbon monoxide
1.472
0.03948
COS
Carbon oxysulphide
6.975
0.06628
CO2
Carbon dioxide
3.658
0.04286
CS2
Carbon disulphide
11.25
0.07262
CHCl3
Trichloromethane
15.34
0.1019
CHF3
Trifluoromethane
5.378
0.06403
CH2Cl2
Dichloromethane
12.44
0.08689
CH2F2
Difluoromethane
6.184
0.06268
CH3Cl
Chloromethane
7.566
0.06477
CH3F
Fluoromethane
5.009
0.05617
NH3NO2
Nitromethane
17.18
0.1041
CH4
Methane
2.300
0.04301
CH3OH
Methanol
9.472
0.06584
CH3SH
Methanethiol
8.911
0.06756
CH3NH2
Methylamine
7.106
0.05879
C2Cl2F3
1,1,2-Trichlorotrifluoroethane
20.25
0.1481
C2F4
Tetrafluoroethylene
6.954
0.08085
C2N2
Cyanogen
7.803
0.6952
C2H2
Acetylene
4.516
0.05220
C2H2F2
1,1-Difluoroethylene
6.000
0.07058
C2H3Cl3
1,1,1-Trichloroethane
20.15
0.1317
C2H3F
Fluroethylene
5.984
0.06504
C2H3F3
1,1,1-Trifluoroethane
9.302
0.09572
C2H3N
Acetonitrile
17.89
0.1169
C2H4
Ethylene
4.612
0.05821
C2H4Cl2
1,1-Dichloroethane
15.73
0.1072
C2H4Cl2
1,2-Dichloroethane
17.0
0.108
C2H4O
Ethylene oxide
8.922
0.06779
CH3COOH
Acetic acid
17.71
0.1065
C2H4O2
Methyl formate
11.54
0.08442
C2H5Br
Bromoethane
11.89
0.08406
C2H5Cl
Chloroethane
11.7
0.090
C2H5F
Fluoroethane
8.170
0.07758
C2H6
Ethane
5.570
0.06499
C2H6O
Dimethyl ether
8.690
0.07742
C2H5OH
Ethanol
12.56
0.08710
C2H5SH
Dimethyl sulphide
13.34
0.09453
C2H5SH
Ethanethiol
13.23
0.09447
C2H7N
Dimethylamine
10.44
0.08510
C2H7N
Ethylamine
10.79
0.08433
C3F8
Perfluoropropane
12.96
0.1338
C3H5N
Propanenitrile
21.57
0.1369
C3H6
Propene
8.438
0.08242
C3H6
Cyclopropane
8.293
0.07420
C3H6O
Acetone
16.02
0.1124
C3H6O
Propanal
14.08
0.09947
C3H6O2
Ethyl formate
15.91
0.1115
C3H6O2
Methyl acetate
15.75
0.1108
C3H6O2
Propanoic acid
23.49
0.1386
C3H7Cl
1-Chloropropane
16.11
0.1141`
C3H8
Propane
9.385
0.09044
C3H8O
1-Propanol
16.26
0.1080
C3H8O
2-Propanol
15.82
0.1109
C3H8O
Ethyl methyl ether
12.70
0.1034
C3H8S
Ethyl methyl sulphide
19.45
0.1300
C3H9N
Propylamine
15.26
0.1094
C3H9N
Trimethylamine
13.37
0.1101
C4H4O
Furan
12.74
0.0926
C4H4S
Thiophene
17.21
0.1058
C4H4N
Pyrrole
18.82
0.1049
C4H6
1,3-Butadiene
12.17
0.1020
C4H6O3
Acetic anhydride
26.8
0.157
C4H7N
Butanenitrile
25.76
0.1568
C4H8
1-Butene
12.76
0.1084
C4H8
Cyclobutane
12.39
0.0960
C4H8O
2-Butanone
19.97
0.1326
C4H8O
Tetrahydrofuran
16.39
0.1082
C4H8O2
1,4-Dioxane
19.29
0.1171
C4H8O2
Ethyl acetate
20.57
0.1401
C4H8O2
Methyl propanoate
20.51
0.1377
C4H8O2
Propyl formate
20.79
0.1377
C4H8O2
Butanoic acid
28.18
0.1609
C4H9N
Pyrrolidine
16.84
0.1056
C4H10
Butane
13.93
0.1168
C4H10
Isobutane
13.36
0.1168
C4H10O
1-Butanol
20.90
0.1323
C4H10O
2-Methyl-2-propanol
18.81
0.1324
C4H10O
2-Methyl-1-propanol
20.35
0.1324
C4H10O
Diethyl ether
17.46
0.1333
C4H10S
Diethyl sulphide
22.85
0.1462
C4H11N
Butylamine
19.41
0.1301
C4H11N
Diethylamine
19.40
0.1383
C4H12Si
Tetramethylsilane
20.81
0.1653
C5H4O2
Furfural
22.23
0.1182
C5H5N
Pyridine
19.77
0.1137
C5H8
Cyclopentene
15.61
0.1097
C5H10
1-Pentene
17.86
0.1370
C5H10
2-Methyl-1-butene
16.9
0.129
C5H10
2-Methyl-2-butene
17.26
0.1279
C5H10
Cyclopentane
16.94
0.1180
C5H10O
Tetrahydropyran
20.02
0.1247
C5H10O2
Isobutyl formate
22.82
0.1476
C5H10O2
Propyl acetate
26.23
0.1700
C5H10O2
Ethyl propanoate
25.86
0.1688
C5H10O2
Methyl butanoate
25.83
0.1661
C5H10O2
Methyl isobutanoate
24.87
0.1639
C5H11N
Piperidine
20.84
0.1250
C5H12
Pentane
19.13
0.1451
C5H12
Isopentane
18.29
0.1415
C5H12
Neopentane
17.17
0.1410
C5H12O
1-Pentanol
25.81
0.1564
C6H5Br
Bromobenzene
28.96
0.1541
C6H5Cl
Chlorobenzene
25.80
0.1454
C6H5F
Fluorobenzene
20.10
0.1279
C6H5I
Iodobenzene
33.54
0.1658
C6H6
Benzene
18.82
0.1193
C6H5OH
Phenol
22.93
0.1177
C6H5NH2
Aniline
29.14
0.1486
C6H10O
Cyclohexanone
31.1
0.170
C6H11N
Hexanenitrile
35.50
0.1996
C6H12
Cyclohexane
21.95
0.1413
C6H11OH
Cyclohexanol
28.93
0.1586
C6H12O2
Pentyl formate
27.97
0.1730
C6H12O2
Isobutyl acetate
29.05
0.1845
C6H12O2
Ethyl butanoate
30.53
0.1922
C6H12O2
Ethyl 2-methylpropanoate
29.05
0.1872
C6H12O2
Methyl pentanoate
29.39
0.1847
C6H14
Hexane
24.97
0.1753
C6H14
2,3-Dimethylbutane
23.29
0.1660
C6H14O
1-Hexanol
31.35
0.1829
C6H15N
Triethylamine
27.59
0.1836
C6H15N
Dipropylamine
24.82
0.1591
C7H5N
Benzonitrile
33.89
0.1727
C7H6O
Benzaldehyde
30.30
0.1553
C7H8
Toluene
24.89
0.1499
C7H8O
o-Cresol
28.33
0.1447
C7H8O
m-Cresol
31.86
0.1609
C7H8O
p-Cresol
28.11
0.1422
C7H8O
Benzyl alcohol
34.7
0.173
C7H8O
Anisole
28.60
0.1579
C7H16
Heptane
30.89
0.2038
C7H15OH
Heptanol
37.22
0.2097
C8H10
Ethylbenzene
30.86
0.1782
C8H10
o-Xylene
31.06
0.1756
C8H10
m-Xylene
31.41
0.1814
C8H10
p-Xylene
31.54
0.1824
C8H10O
Phenetole
35.70
0.1966
C8H11N
N,N-Dimethylaniline
37.92
0.1967
C8H18
Octane
37.86
0.2372
C8H18
2,5-Dimethylhexane
35.49
0.2299
C8H18O
1-Octanol
43.42
0.2371
C9H7N
Quinoline
36.70
0.1672
C9H12
Cumene
36.20
0.2044
C9H12
Propylbenzene
37.14
0.2073
C9H12
1,2,4-Trimethylbenzene
38.03
0.2088
C9H12
Mesitylene
37.87
0.2118
C9H20 Nonane
45.11
0.2702
C9H20O
1-Nonanol
50.00
0.2654
C10H8
Naphthalene
40.32
0.1920
C10H14
Butylbenzene
44.07
0.2378
C10H14
Isobutylbenzene
40.40
0.2215
C10H14
o-Cymene
42.7
0.234
C10H14 p-Cymene
45.27
0.2478
C10H14
p-Diethylbenzene
45.03
0.2439
C10H14
1,2,4,5-Tetramethylbenzene
45.8
0.24
C10H22
Decane
52.88
0.3051
C10H22O
1-Decanol
57.45
0.2971
C11H24
Undecane
60.88
0.3396
C12H10
Biphenyl
47.16
0.2130
C12H26
Dodecane
69.14
0.3741
C12H26O
1-Dodecanol
72.69
0.3598
C13H12
Diphenylmethane
60.46
0.2798
C13H28
Tridecane
77.94
0.4109
C13H28O
1-Tridecanol
81.20
0.3942
C14H30O
1-Tetradecanol
89.91
0.4289
C15H32
Pentadecane
96.50
0.4857