Qualitative understanding of partition preferences

Introduction
Cavity model
Rules for partitioning
The cavity model in quantitative terms

Selftest
Problems
     1) Give a qualitative explanation
     2) Estimate the extraction efficiency
           Answer
     3) Assign partition constants to substances
           Answer
     4) Fuel accident
           Answer
     5) Mixture of similar isomeres ... ?
           Answer
     6) Extraction with pentane or diethyl ether?
     7) Prediction of partition constants
           Answer
     8) Assign data to substances
           Answer
     9) Explain saturated vapor pressure
     10) Apolar surface
Intermolecular interactions in every day life
FAQ

1) Give a qualitative explanation

The table below lists measurement values for the partitioning between hexadecane and air at 25°C:

Substance

Log Khexadecane/air
(L/L)

Log K humic acid/air
(L/L)

Octane

3.67

2.31

Octane-2-on

4.26

4.86

Octane-1-ol

4.61

6.29

 

Which conclusions can you draw from the following statements on differences between hexadecane and humic acids?:

  • Octane-2-on and octane-1-ol sorb more than octane to the hexadecane-phase.

  • Octane is not sorbed as strongly to humic acids as to hexadecane. The opposite is true for octane-2-on and octane-1-ol.

  • The increase of sorption coefficients in the order n-octane < octane-2-on < octane-1-ol is more pronounced in humic acids than in hexadecane.

 

You will have to check your answer to this question by yourself ...

 

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