The Liebig condenser, named after the German chemist Justus von Liebig, is a type of laboratory glass condenser commonly used in chemical reactions. It consists of a cylindrical glass body with an inner tube that is open at both ends and an outer jacket that is open at one end.

The jacket is used to circulate a cooling fluid, usually water or air, to remove heat from the reaction mixture. This helps to condense the reaction vapors and collect the condensate in a receiver. The design allows for efficient heat transfer and makes it a versatile tool for many types of chemical reactions.