U4-2-1 - Solvent Extraction

Question 1

Name this piece of equipment

Answer 1

Separating funnel

Question 2

What is a separating funnel used for?

Answer 2

To separate immiscible liquids

Question 3

Which layer is more likely to be at the bottom of a separating funnel:
aqueous or organic?

Answer 3

Aqueous

EXCEPT when using halogenated solvents like DCM

Question 4

To carry out a solvent extraction:
* add mixture to a ____________________
* shake
* leave to separate into layers
* run off lower layer.

Answer 4

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* leave to separate into layers
* run off lower layer.

Question 5

What should be used to remove water (impurity) during solvent extraction?

Answer 5

Drying agent (e.g. anhydrous calcium chloride)

Question 6

To carry out a solvent extraction:
* add mixture to a separating funnel
* ____________
* leave to separate into layers
* run off lower layer.

Answer 6

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* leave to separate into layers
* run off lower layer.

Question 7

How should a solvent be chosen for solvent extraction?

Answer 7

Any one of:
* volatile/low b.p.
* unreactive with the solute
* solute should be more soluble in it than the original solvent
* immiscible with original solvent.

Question 8

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* ____________________
* run off lower layer.

Answer 8

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* leave to separate into layers
* run off lower layer.

Question 9

Which is better for solvent extraction:
* one extraction with a larger volume
* multiple extractions with smaller volumes?

Answer 9

Multiple extractions with smaller volumes - a greater percentage of stuff will be extracted.

Question 10

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* leave to separate into layers
* ____________________.

Answer 10

To carry out a solvent extraction:
* add mixture to a separating funnel
* shake
* leave to separate into layers
* run off lower layer.