Flasks Boiling, Flat Bottom class A uses include mixing and heating solutions, short term storage and for research involving testing accessories such as chemical probes and sensors. A chemical probe is a small molecule used in the study and manipulation of biological systems like cells or organisms. Round-bottom 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 distilling flasks for distillations or boiling chemical reactions to allow a nucleation site for gradual boiling