Question

If you need to extract a 50 ml aqueous solution with 50 ml of dichloromethane, what is the minimum size of a separatory funnel you will have to use to safely carry out this procedure? briefly explain your answer.

Answer 1

The dichloromethane (DCM) has less density than water and also the polarity of water is much more than DCM. So the mixture of water and dichloromethane will always be a heterogeneous mixture. In the mixture dichloromethane will be always up of the water layer. The volume of the separatory funnel which contains the mixture of DCM and water must have to be more than the total volume of the liquids thus the volume of the funnel will be more than (50+50) = 100mL.

The caution have to consider during the separation are-

1. The separatory funnel have to shake well with lid and have to settle down for some times until the two liquid separated.

2. The lid should be open very slowly as the vapor pressure of DCM is more and it will float on the water.

3. After this the stopcock should be opened and slowly the water will come out first followed by DCM.