Separatory Funnel Extraction

initial mass of compound (grams)

1

volume of phase 1 (mL)

1

volume of phase 2 (mL)

1

number of extractions n

1

2

3

4

5

6

7

8

9

10

partition coefficient (Kp)

1

comparison

line graph

quantitative

bar graph

equation for mass extracted:

inital mass-initial mass ×

number of extractions

volume phase 1

(partition coefficient × volume phase 2) + volume phase 1

extractions	mass extracted	mass remaining	volume of phase 2 used
1	0.5	0.5	1

A separatory funnel is often used to remove a compound from a mixture (called phase 1) by mixing it with a different solvent (called phase 2) that is immiscible (will not mix) with phase 1. The partition coefficient of the compound is the solubility of the compound in phase 2 divided by the solubility of the compound in phase 1. Thus a phase 2 that has the greatest partition coefficient will be chosen to extract the compound. The best way to extract a compound from a mixture is to use either a phase 2 for which the compound is very soluble (seen by increasing the partition coefficient) or a greater volume of phase 2 compared to phase 1.

A large number of extractions with smaller volumes is more efficient then a single extraction with a large phase 2 volume, as you can see in the bar graph tab as the number of extractions is increased.