Distilling flasks are used to separate mixtures of two liquids with different boiling points. A variety of designs and capacities are available to accommodate distillation processes of varying complexities. Flask design typically features a distillation column in the form of a long neck, a side arm that facilitates condensation, and a round bottom for uniform heat distribution. For complex distillations, flasks with two or more necks that allow for connection to multiple components are available. Neck joints come in a variety of sizes, orientations, and joint types. Distilling flasks are manufactured from heat and chemical resistant materials, such as borosilicate glass or PFA.

Distilling flasks, also known as distillation flasks, are types of laboratory flasks forming part of larger distillation assemblies used for the separation and/or purification of liquids or liquid mixtures where the components have different boiling points. Distillation flasks are used to contain and heat the liquid(s) that require purification. They are round-bottomed for uniform heat distribution, with a stoppered or jointed neck of variable length, to which is attached a downward-sloping, inclined side-arm for connection to a condensing unit or similar component to cool the heated vapors back down to their liquid state. For complex distillations, flasks with two or more necks that allow for connection to multiple components are available.

Distilling flasks are usually made of a high-quality glass, such as borosilicate, for heat and chemical resistance and for reusability. Heating mantles are the preferred heat source for improved temperature control and for safety reasons, but direct flame heat sources are also used. Immersion thermometers can also be introduced into the neck of the flasks to monitor the temperature of the distillation process.

Distilling flasks are available in a range of capacities, and the neck joints come in a variety of sizes, orientations, and joint types.

What are distillation flasks used for?

• Separation and purification of miscible liquid mixtures in organic chemistry
• Drying off solid residues and/or solvent removal
• Distilling off liquids from polymers and petroleum products
• Removal of particulates or other solid contaminants
• As part of a water purification system for production of distilled water for laboratory use