Engineering
Antoine Vapor Pressure Equation & Vacuum Boiling Point Temperature
Estimate water saturation pressure and invert the Antoine correlation within the documented 1–100°C range, using mmHg absolute pressure.
An empirical correlation with a stated temperature range
This worked water example uses A=8.07131, B=1730.63 and C=233.426 for temperature in Celsius and saturation pressure in mmHg. WaterTAP documents this coefficient set for 1–100°C. It is not a universal NIST coefficient set: published sets may use different pressure units, temperature units and ranges.
The inverse estimates saturation temperature for a positive absolute pressure only when the result lies within the coefficient range. It does not determine a boiling temperature at any arbitrary pressure, nor model mixture boiling, nucleation, pressure drops or transient operation.
The 253-mmHg case is a hypothetical low-pressure example. It does not establish the atmospheric pressure on Mount Everest, which varies. The correlation predicts about 760.1mmHg at 100°C; this is an approximation, not an exact equality to the defined standard atmosphere of 760mmHg.
Keep the three coefficients together when experimenting. This page validates the supplied water set so swapping one constant cannot silently retain the wrong validity range. Other substances need their own documented parameter sets and range checks.
| Thermodynamic Property (Water) | Antoine Formula | Value | Engineering Meaning |
|---|---|---|---|
| Vapor Pressure at 100 °C | 10 ^ (B2 - (B3 / (B4 + 100))) | 760.1 mmHg | Approximate normal-pressure result |
| Vapor Pressure at 25 °C | 10 ^ (B2 - (B3 / (B4 + 25))) | 23.69 mmHg | Pure-water saturation pressure |
| Boiling Temp at 253 mmHg | (B3 / (B2 - LOG10(253))) - B4 | 71.9 °C | Hypothetical absolute pressure |
Saturation Vapor Pressure P = 10^(A - (B / (C + T)))
Always match units of temperature T (C vs K) and pressure P (mmHg, bar, or kPa) to the published Antoine table for A, B, and C.
=IF(COUNT(B2:B5)<>4,"Invalid inputs",IF(OR(B2<>8.07131,B3<>1730.63,B4<>233.426),"Use documented coefficient set",IF(OR(B5<1,B5>100),"Outside 1-100 C range",ROUND(10^(B2-B3/(B4+B5)),1))))Inverse saturation temperature within the same range
Validate the unrounded inverse result before reporting temperature to one decimal place. Use absolute pressure in mmHg, not gauge pressure.
=IF(COUNT(B2:B4,B6)<>4,"Invalid inputs",IF(OR(B2<>8.07131,B3<>1730.63,B4<>233.426),"Use documented coefficient set",IF(B6<=0,"Positive absolute pressure required",IF(B2-LOG10(B6)<=0,"Outside 1-100 C range",LET(boilTemp,B3/(B2-LOG10(B6))-B4,IF(OR(boilTemp<1,boilTemp>100),"Outside 1-100 C range",ROUND(boilTemp,1)))))))Try the example
Use the original values or change them to test your understanding.