It is a two neck or double neck round bottom flask having side neck parallel.It is used for distillation purposes.It has a Glass stopcock which is a constant pressure retention device.It has conical ground joints.It is manufactured from heat resistant boro-silicate glass.It comes in various capacities and stop cock size also varies according to the capacity of the flask.It has a heavy wall.Flask outer diameter also varies according to its size.It has two necks one at center and other at side. It is used as a Laboratory glassware mostly for chemical and biochemical work. Its sizes are usually inscribed on glass. The ends of the necks are usually conical ground glass joints. They are standardized. Because of the round bottom, cork rings are needed to keep the round bottom flasks upright. When in use, round-bottom flasks are commonly held at the neck by clamps on a stand. they allow more uniform heating and boiling of liquid. These flasks are often used to contain chemical reactions run by chemists, especially for reflux set-ups and laboratory-scale synthesis.
Boiling chips are added in these distilling flasks for distillations or boiling chemical reactions to allow a nucleation site for gradual boiling. This nucleation avoids a sudden boiling surge where the contents may overflow from the boiling flask. Stirring bars or other stirring devices suited for these round-bottom flasks are sometimes used. For a reflux set-up, a condenser is typically attached to the middle or only neck of the flask being used. Additional necks on a flask could allow a thermometer or a mechanical stirrer to be inserted into the flask contents.
