Vapor Pressure Estimates – Using Antoine Equation
One of the most common uses for vacuum pumps is to cause chemicals to evaporate. But how much vacuum is needed to make a certain chemical evaporate? One way to estimate the vapor pressure of a given chemical compound is to use the Antoine Equation.
The table below provides reference data on Antoine equation coefficients that has been published in the NIST Chemistry WebBook for a variety of common chemicals. The form of the Antoine equation used here is:
log10(P) = A – [B / (T + C)],
where P is the calculated vapor pressure in bar (on an absolute scale) and T is the temperature in Kelvin. Using the reference data assembled by NIST, you can plug in the values for A, B, and C to estimate the vapor pressure, P.
| Chemical | Coefficient ‘A’ | Coefficient ‘B’ | Coefficient ‘C’ | Applicable Temp. Range (K) |
|---|---|---|---|---|
| Acetic Acid | 4.68206 | 1642.54 | -39.764 | 290.26 – 391.01 |
| Acetic Acid Anhydride | 4.24655 | 1427.77 | -75.113 | 335.99 – 412.57 |
| Acetone | 4.42448 | 1312.253 | -32.445 | 259.16 – 507.6 |
| Acetonitrile | 4.27873 | 1355.374 | -37.853 | 288.3 – 362.3 |
| Benzene | 4.01814 | 1203.835 | -53.226 | 287.7 – 354.07 |
| iso-Butanol | 4.43126 | 1236.991 | -101.528 | 353.36 – 388.77 |
| n-Butanol | 4.54607 | 1351.555 | -93.34 | 295.8 – 391.0 |
| tert-Butanol | 4.49774 | 1174.869 | -93.92 | 312.66 – 355.56 |
| Carbon Tetrachloride | 4.02291 | 1221.781 | -45.739 | 293.03 – 350.86 |
| Chlorobenzene | 4.11083 | 1435.675 | -55.124 | 335.19 – 404.88 |
| Chloroform | 4.20772 | 1233.129 | -40.953 | 215 – 334.4 |
| Cyclohexane | 3.96988 | 1203.526 | -50.287 | 293.06 – 354.73 |
| Cyclopentane | 4.00288 | 1119.208 | -42.412 | 288.86 – 323.18 |
| Dimethyl Acetamide | 6.09451 | 2725.96 | 28.209 | 303 – 363 |
| Dimethyl Formamide | 3.93068 | 1337.716 | -82.648 | 303 – 363 |
| Dimethyl Sulfoxide | 5.23039 | 2239.161 | -29.215 | 293 – 323 |
| Dioxane | 4.58135 | 1570.093 | -31.297 | 293 – 378 |
| Ethanol | 5.37229 | 1670.409 | -40.191 | 273 – 351.70 |
| Ethyl Acetate | 4.22809 | 1245.702 | -55.189 | 288.73 – 348.98 |
| Ethyl Ether | 4.022 | 1062.64 | -44.93 | 250.04 – 328.57 |
| Ethylene Dichloride | 4.58518 | 1521.789 | -24.67 | 242.33 – 372.6 |
| Ethylene Glycol | 4.97012 | 1914.951 | -84.996 | 323 – 473 |
| Heptane | 4.02832 | 1268.636 | -56.199 | 299.07 – 372.43 |
| n-Hexane | 4.00266 | 1171.53 | -48.784 | 286.18 – 342.69 |
| Hydrochloric Acid | 4.57389 | 868.358 | 1.754 | 188.3 – 309.4 |
| Methanol | 5.20409 | 1581.341 | -33.5 | 288.1 – 356.83 |
| Methylene Chloride | 4.53691 | 1327.016 | -20.474 | 233 – 313 |
| Pentane | 3.9892 | 1070.617 | -40.454 | 268.8 – 341.37 |
| iso-Propanol | 4.57795 | 1221.423 | -87.474 | 395.1 – 508.24 |
| n-Propanol | 5.31384 | 1690.864 | -51.804 | 292.4 – 370.5 |
| Pyridine | 4.16272 | 1371.358 | -58.496 | 340.5 – 426.04 |
| Tetrahydrofuran | 4.12118 | 1202.942 | -46.818 | 296.29 – 372.8 |
| Toluene | 4.14157 | 1377.578 | -50.507 | 273 – 323 |
| Water | 6.20963 | 2354.731 | 7.559 | 293 – 343 |