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.