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Chemistry · Glossary

What is Distillation under reduced pressure?

Definition 35.12 University Chemistry — Year 2 · Chapter 35 — Lab Techniques II: Synthesis and Analysis in Practice

A distillation under reduced pressure is carried out in an apparatus connected to a vacuum pump through a manometer, at a pressure where the liquid boils at a temperature it can stand.

Boiling temperature against pressure () with the enthalpies of vaporisation and boiling points of the NIST WebBook. The circles are measured boiling points at 7 and 13\, mbar, not used in the curves: the simple equation is within a few kelvin. Lowering the pressure from 1 bar to 20\, mbar lowers the boiling points by more than 100\, K.
Boiling temperature against pressure (Proposition 35.13) with the enthalpies of vaporisation and boiling points of the NIST WebBook. The circles are measured boiling points at 7 and 13 mbar13\,\mathrm{mbar}, not used in the curves: the simple equation is within a few kelvin. Lowering the pressure from 1 bar to 20 mbar20\,\mathrm{mbar} lowers the boiling points by more than 100 K100\,\mathrm{K}.
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