Antoine Constant

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)  -
  
  • \(A \;=\; 8.07131\)
    
  • \(B \;=\; 1730.63\)
    
  • \(C \;=\; 233.426\)
    

• For the temperature range 99°C to 374°C (or 372.15 °K to 647.15 °K)  -

  • \(A \;=\; 8.14019\)
    
  • \(B \;=\; 1810.94\)
    
  • \(C \;=\; 244.485\)
    

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	\(K\)	\(C\)