The Antoine constants are used in the Antoine equation to estimate the vapor pressure of a substance.
For water, the Antoine constants depend on the temperature range
Here are two common sets of constants for water -
- For the temperature range 1°C to 100°C (or 273.15 °K to 373.15 °K) -
- \(A \;=\; 8.07131\)
- \(B \;=\; 1730.63\)
- \(C \;=\; 233.426\)
- \(A \;=\; 8.07131\)
-
For the temperature range 99°C to 374°C (or 372.15 °K to 647.15 °K) -
- \(A \;=\; 8.14019\)
- \(B \;=\; 1810.94\)
- \(C \;=\; 244.485\)
- \(A \;=\; 8.14019\)
Units for the Constants
- A is dimensionless
- B in degrees Celsius (°C) or Kelvin (°K)
- C in degrees Celsius (°C) or Kelvin (°K)
The vapor pressure P is typically expressed in mmHg (torr) when using the Antoine equation. A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly 133.322387415 pascals or exactly 133.322 pascals. It is denoted mmHg or mm Hg.
Antoine constant Formula |
||
| \( log_{10} \; (P) \;=\; A - (B \;/\; C + T) \) | ||
| Symbol | English | Metric |
| \( P \) = vapor pressure | - | \(mmHg\) |
| \( A \) = Antoine constant | \(dimensionless\) | \(dimensionless\) |
| \( B \) = Antoine constant | \(K\) | \(C\) |
| \( C \) = Antoine constant | \(K\) | \(C\) |
| \( T \) = temperature | \(K\) | \(C\) |
