Solvent Extraction:
How can we tell which phase is aqueous and which is organic?
Rotary Evaporator:
Why do we rotate the flask while it is heating in water?
It will evaporate all the solvent (Dichloromethane), leaving the caffeine crystals on the inside of the flask.
Why do we need a condenser?
The condenser will condense all the solvent's vapour, and in turn collect it in a flask.
What is the benefit to work under vacuum?
It brings down the boiling point of the substance.