Enter the pressure in kPa and the temperature in °C into the calculator to determine the missing value.
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kPa to Temperature Formula
The Antoine equation relates saturation vapor pressure to temperature for water and common solvents. Constants below assume pressure in mmHg and temperature in °C; the calculator converts to kPa automatically.
P = 10^(A - (B/(T+C))) * (101.325/760) T = (B/(A - log10(P*760/101.325)))- C
- P = pressure (kPa)
- T = temperature (°C)
- A, B, C = Antoine constants (substance-specific; see table below)
| Substance | A | B | C | Valid Range (°C) | Normal BP (°C) |
|---|---|---|---|---|---|
| Water | 8.07131 | 1730.63 | 233.426 | 1 to 100 | 100.0 |
| Ethanol | 8.20417 | 1642.89 | 230.3 | -57 to 80 | 78.4 |
| Acetone | 7.11714 | 1210.595 | 229.664 | -13 to 55 | 56.1 |
| Methanol | 8.07240 | 1582.271 | 239.726 | -10 to 80 | 64.7 |
| Ammonia | 7.36008 | 926.069 | 240.000 | -83 to 60 | -33.4 |
| Benzene | 6.90565 | 1211.033 | 220.790 | 8 to 80 | 80.1 |
| Toluene | 6.95465 | 1344.800 | 219.482 | 6 to 100 | 110.6 |
| Source: NIST Chemistry WebBook; Poling, Prausnitz & O'Connell, "The Properties of Gases and Liquids," 5th ed. Normal BP at 101.325 kPa. Constants only valid within stated ranges. | |||||
| Pressure (kPa) | Temperature (°C) | Temperature (°F) |
|---|---|---|
| 0.2 | -14.13 | 6.57 |
| 0.5 | -2.54 | 27.43 |
| 1 | 7.07 | 44.73 |
| 2 | 17.57 | 63.63 |
| 3 | 23.97 | 75.15 |
| 5 | 32.97 | 91.35 |
| 7 | 38.87 | 101.97 |
| 10 | 45.87 | 114.57 |
| 13 | 51.17 | 124.11 |
| 16 | 55.39 | 131.70 |
| 20 | 60.47 | 140.85 |
| 25 | 65.04 | 149.07 |
| 30 | 69.49 | 157.08 |
| 40 | 75.75 | 168.35 |
| 50 | 81.43 | 178.57 |
| 60 | 85.99 | 186.78 |
| 70 | 89.99 | 193.98 |
| 80 | 93.56 | 200.41 |
| 90 | 96.72 | 206.10 |
| 101.325 | 100.00 | 212.00 |
| Water saturation temperature via Antoine equation (A=8.07131, B=1730.63, C=233.426). Conversion: mmHg = kPa x 760/101.325. Valid approximately 1 to 100 °C. | ||
Boiling Point of Water by Altitude
Atmospheric pressure decreases with altitude, directly lowering water's boiling point. This affects cooking times, food safety, and equipment calibration at elevation.
| Location | Altitude (m) | Pressure (kPa) | Boiling Point (°C) | Boiling Point (°F) |
|---|---|---|---|---|
| Sea level | 0 | 101.3 | 100.0 | 212.0 |
| Denver, CO, USA | 1,609 | 83.4 | 94.7 | 202.5 |
| Mexico City, Mexico | 2,240 | 77.1 | 92.6 | 198.7 |
| Lhasa, Tibet | 3,656 | 64.4 | 87.8 | 190.0 |
| Everest Base Camp | 5,364 | 51.5 | 82.1 | 179.8 |
| Mt. Everest Summit | 8,849 | 31.4 | 70.2 | 158.4 |
| Pressures from ICAO standard atmosphere model. Temperatures calculated via Antoine equation (water constants). Practical implication: pasta takes 25% longer to cook at Everest Base Camp due to the 18°C lower boiling point. | ||||
Industrial and Scientific Reference Points
| Application | Pressure (kPa abs) | Temp (°C) | Notes |
|---|---|---|---|
| Water triple point | 0.6113 | 0.01 | Only state where solid, liquid, and vapor coexist |
| Normal boiling point | 101.325 | 100.0 | Standard atmosphere (1 atm = 14.696 psi) |
| Home pressure cooker | 170–207 | 115–121 | Typically 10–15 psi gauge; reduces cook time 30–50% |
| Standard autoclave sterilization | 206.8 | 121 | 15 psi gauge; 15–20 min destroys all organisms incl. spores (ISO 17665-1) |
| Flash autoclave sterilization | 241.3 | 127 | 20 psi gauge; 3-min unwrapped instrument cycle |
| Water critical point | 22,064 | 374.1 | Above this point, liquid and vapor phases are indistinguishable (IAPWS-IF97) |
| Autoclave standards per ISO 17665-1 and WHO sterilization guidelines. Triple point and critical point from IAPWS-IF97. | |||
FAQ
What do the Antoine constants A, B, and C represent?
Empirically fitted constants specific to each substance, derived from experimental vapor pressure measurements. Higher B values indicate stronger intermolecular forces: water (B=1730.63) versus acetone (B=1210.595). Constants are only valid within their stated temperature range; extrapolation produces increasing error outside that range.
Why use the Antoine equation over Clausius-Clapeyron?
The Clausius-Clapeyron equation assumes constant enthalpy of vaporization, introducing 1–3% error over wide temperature spans. The Antoine equation fits experimental data directly and achieves ±0.1% accuracy within its valid range. For water above 100°C, use the high-temperature Antoine constants (A=8.14019, B=1810.94, C=244.485, valid 60–150°C) or IAPWS-IF97 steam tables.
Which substances does the Materials tab support?
Water, ethanol, acetone, methanol, ammonia, benzene, and toluene. For other substances, obtain A, B, C constants from the NIST Chemistry WebBook and apply the formula directly. The constants in the table above match those used in the calculator.