Lydersen method

The Lydersen method is a group contribution method for the estimation of the critical sizes, and. The Lydersen method is a model for many later models after Joback, Ambrose, Constantinou and Gani and Others The Lydersen method is based in the case of estimation of the critical temperature on the Guldberg rule, which relates the critical temperature in a ratio to the normal boiling point.

Determining equations

• Critical temperature:
• Critical pressure:
• Critical volume:

Is the normal boiling point, the molar mass, group contributions are (different for each size ) for functional groups of a molecule.

Group contributions

Example calculation

Acetone is separated into two different fragments, a carbonyl group and two methyl groups. For the critical volume, the following calculation:

The literature values ​​are from 215,90 cm3, 230.5 cm3 and 209.0 cm3.