A rotary evaporator (or rotavap)^[1] is commonly used in chemical laboratories to remove solvents by evaporation.

The liquid is put in a round-bottomed flask and placed in the device. The rotavap spins and heats the flask and reduces the pressure inside by creating a vacuum. The vacuum makes the liquid evaporate at a low temperature than normal. The liquid becomes a gas and is collected by cooling it so it condenses into another flask.

If there are substances dissolved in the liquid they will be left behind in when it evaporates. If water with salt dissolved in it is evaporated, then pure water and dry salt will be separated. Scientists use rotary evaporators to remove the liquid a solid is dissolved in.

Rotary evaporators are often quicker to use than evaporating basins. They can be used for distillations.

1. ↑ Laurence M. Harwood, Christopher J. Moody (13 Jun 1989). Experimental organic chemistry: Principles and Practice (Illustrated ed.). pp. 47–51. ISBN 9780632020171.