Round Bottom Flasks
Round-bottom flasks (also called round-bottomed flasks, Flasks, round bottom, or RB Flasks)having spherical bottoms are more resistant to fracturing under vacuum, as a sphere more evenly distributes stress across its surface. Because of the spherical 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 flask clamps on a stand.
The flasks are usually used in heating or boiling a liquid, in distillation as distilling flasks and receiving flasks for the distillate,used as the distilling flasks in rotary evaporators.