# A8: van der Waal's Constants for Real Gases

The van der Waal's equation of state for a non-ideal (real) gas is:

$\left(P + \dfrac{an^2}{V^2}\right) (V − nb)=nRT$

• 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