In industrial operations, pressure varies continuously with pressure, which makes standard boiling point values insufficient for practical use.Whether you are working with vacuum distillation, high-pressure systems, or process design calculations, you need a reliable way to determine the actual phase-change temperature under operating conditions.
Our Boiling Point Calculator is built to solve this exact problem. It uses the Antoine Equation, a widely accepted thermodynamic model, to calculate boiling point with high accuracy across different pressures. The calculation is based on three substance-specific constants (A, B, and C), ensuring results that are suitable for both academic analysis and real plant applications.
What is the Boiling Point?
The boiling point of a substance is the temperature at which its vapor pressure equals the surrounding atmospheric pressure. At this point, the liquid transitions into a gas. Because atmospheric pressure varies with altitude and process conditions, a reliable calculator is necessary to determine the specific temperature required for phase change at any given pressure.
What is the Antoine Equation?
The equation is an empirical mathematical expression that describes the relationship between vapor pressure and temperature for pure substances.
The standard formula is:
![\[\log_{10}P = A - \frac{B}{T + C}\]](http://chemicaltweak.b-cdn.net/wp-content/ql-cache/quicklatex.com-b1c02fd35721546fdc76198c297e4013_l3.png "Rendered by QuickLaTeX.com")
Where:
- P: Vapor Pressure (mmHg).
- T: Temperature (°C).
- A, B, C: Substance-specific coefficients
If you do not have the Antoine constants but know the heat of vaporisation, you can use our Vapor Pressure Calculator (Clausius-Clapeyron) for your estimations as boiling points can also be estimated using the Clausius-Clapeyron Equation.
Antoine Equation vs. Clausius-Clapeyron Equation
| Feature | Antoine Equation | Clausius-Clapeyron |
| Accuracy | High (uses 3 specific constants) | Moderate (theoretical approximation) |
| Data Needed | Constants A, B, and C | Enthalpy of Vaporization ( ) |
| Best For | Specific industrial chemicals and solvents | General thermodynamic calculations and unknown substances |
Technical Reference: Antoine Constants Table
The constants (A, B, C) used in this calculator are curated from the following high-authority thermodynamic databases NIST Chemistry WebBook
| Chemical Name | Formula | Constant A | Constant B | Constant C | Range (°C) |
| Acetone | C3H6O | 7.02447 | 1161 | 224 | -32 to 77 |
| Methyl Ethyl Ketone | C4H8O | 7.06356 | 1261.34 | 221.97 | -6 to 80 |
| Chloroform | CHCl3 | 6.90328 | 1163.03 | 227.4 | 10 to 60 |
| Dichloromethane | CH2Cl2 | 7.0803 | 1138.91 | 231.45 | -40 to 40 |
| Carbon Tetrachloride | CCl4 | 6.9339 | 1242.43 | 227.26 | -20 to 100 |
| Ethyl Acetate | C4H8O2 | 7.10179 | 1244.95 | 217.88 | 15 to 77 |
| Diethyl Ether | C4H10O | 6.92374 | 1064.07 | 228.8 | -61 to 20 |
| Tetrahydrofuran | C4H8O | 6.99515 | 1202.29 | 226.254 | -15 to 67 |
| Dimethyl Sulfoxide | C2H6OS | 7.4038 | 1736 | 206.2 | 20 to 189 |
| Methanol | CH4O | 8.08097 | 1582.271 | 239.726 | 15 to 100 |
| Ethanol | C2H6O | 8.20417 | 1642.89 | 230.3 | -57 to 80 |
| n-Propanol | C3H8O | 7.84767 | 1499.21 | 204.64 | 20 to 120 |
| Isopropanol | C3H8O | 8.11778 | 1580.92 | 219.61 | 0 to 82 |
| n-Butanol | C4H10O | 7.4768 | 1362.39 | 178.77 | 30 to 118 |
| n-Pentanol | C5H12O | 7.18246 | 1287.625 | 161.33 | 50 to 138 |
| Ethylene Glycol | C2H6O2 | 8.09083 | 2088.936 | 203.54 | 50 to 200 |
| Benzene | C6H6 | 6.90565 | 1211.033 | 220.79 | 7 to 80 |
| Toluene | C7H8 | 6.95464 | 1344.8 | 219.48 | 13 to 110 |
| Ethylbenzene | C8H10 | 6.95719 | 1424.25 | 213.2 | 25 to 136 |
| n-Pentane | C5H12 | 6.85221 | 1064.63 | 232 | -50 to 58 |
| n-Hexane | C6H14 | 6.87776 | 1171.53 | 224.366 | -25 to 92 |
| n-Heptane | C7H16 | 6.9024 | 1268.11 | 216.9 | -2 to 124 |
| n-Octane | C8H18 | 6.91868 | 1355.12 | 209.51 | 19 to 152 |
| n-Nonane | C9H20 | 6.93893 | 1431.82 | 202.69 | 38 to 178 |
| n-Decane | C10H22 | 6.95367 | 1495.17 | 193.86 | 58 to 203 |
| Cyclohexane | C6H12 | 6.84498 | 1203.53 | 222.86 | 10 to 81 |
| Isobutane | C4H10 | 6.74048 | 882.8 | 240 | -86 to -12 |
| n-Butane | C4H10 | 6.82485 | 943.453 | 239.711 | -73 to 19 |
| Acetic Acid | CH3COOH | 7.18807 | 1416.7 | 211 | 17 to 118 |
| Sulfuric Acid | H2SO4 | 7.07228 | 2018.75 | 109.5 | 150 to 330 |
| Nitric Acid | HNO3 | 7.42 | 1295.4 | 215.3 | 0 to 83 |
| Formic Acid | CH2O2 | 7.3779 | 1563.28 | 247.07 | 36 to 108 |
| Propionic Acid | C3H6O2 | 7.71423 | 1733.16 | 231.58 | 20 to 141 |
| Ammonia | NH3 | 7.55466 | 1002.71 | 247.88 | -83 to 60 |
| Nitrogen | N2 | 6.49521 | 255.719 | 266.55 | -210 to -190 |
| Oxygen | O2 | 6.69147 | 319.01 | 266.69 | -210 to -173 |
| Hydrogen | H2 | 4.622 | 44.27 | 269.1 | -259 to -248 |
| Propane | C3H8 | 6.80398 | 803.99 | 246.99 | -108 to -25 |
| Carbon Dioxide | CO2 | 6.81228 | 1301.679 | 273.33 | -78 to 31 |
| Water | H2O | 8.07131 | 1730.63 | 233.426 | 1 to 100 |
FAQ
1. Why use the Antoine Equation instead of Clausius-Clapeyron for boiling point calculation?
While the Clausius-Clapeyron equation
is a good theoretical approximation, the Antoine Equation is significantly more accurate for industrial applications. It uses a three-parameter model (A, B, C) that accounts for the curvature of the vapor pressure line more effectively than the simpler two-parameter Clausius-Clapeyron model.
2. Does the boiling point change with altitude?
Yes. Boiling occurs when a liquid’s vapor pressure equals the surrounding atmospheric pressure. Since atmospheric pressure is lower at higher altitudes, the boiling point decreases.
3. How to find the boiling point for a vacuum system?
To find the boiling point under vacuum, enter your target vacuum pressure (e.g., in mmHg or bar) into our Boiling Point Calculator.
4. Is there a limit to the accuracy of these calculations?
Antoine constants are valid only within a specific temperature range (Tmin–Tmax). Using them outside this range can cause large errors. The tool shows a boundary warning when your result is near these limits.
