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Laboratory Glassware: Types of Laboratory Flasks

erlenmeyer flasks beakersFlasks are useful tools for containing liquid and performing mixing, heating, cooling, precipitation, condensation and other processes. They come in a range of sizes, materials and uses. Commonly used laboratory flasks include:
  • An Erlenmeyer flask, conical, or E-flask is one of the most commonly used flasks in scientific laboratories. The flask has a conical base that almost extends into a small, cylindrical neck. This shape allows the flask to be sealed with a bung for heating purposes, while also allowing a researcher the freedom to shake or stir the flask without spilling liquid. The Erlenmeyer flask has diverse uses such as holding and measuring chemical liquid samples, but can also be used to mix, heat and boil chemicals.
  • A Büchner, or sidearm flask is essentially an Erlenmeyer flask (see above) with an additional small tube extending from the side of the neck. The bottom is conical in shape, with a short neck from which the small tube extrudes. The entire flask is made of thick glass. The small side-arm tube is composed of a hose barb, which is a serrated section that catches a thick-walled flexible hose. Because of this design, a Büchner flask is well-equipped for creating vacuums with the help of a Büchner funnel. With the funnel on top of the glass neck and a tube sucking the pressure out of the side, vacuums for sluicing liquids can be created very easily within the flask.
  • A fleaker is a portmanteau of the words flask and beaker, and physically resembles a combination of an Erlenmeyer flask and a beaker. The cylindrical body culminates in a neck that curves inward before flaring out in a rounded opening. Fleakers are generally used for similar applications as Erlenmeyer flasks, but most often only for liquids.
  • A Florence, or boiling flask is a large, round sphere with a long, thin neck and a slightly flared rim opening. The rounded design of the bottom is such that a Bunsen burner can easily heat the solution within. Some Florence flasks are produced with rounded bottoms, and thus need support in order to stand upright; others have flat bottoms and can stand alone. Because they are so often used for boiling, Florence flasks are produced with borosilicate glass to prevent cracking.
  • A retort is a type of flask used primarily for distillation and its design is exclusive to this purpose. The retort resembles an exaggerated teardrop with the middle bent at almost a 90 degree angle. The bulb portion contains a liquid or chemical solution, which is heated to the point of condensation. The condensation then attaches to the roof of the retort, and as it begins precipitating, it runs down the angle of the long, thin point of the tear where there is another opening. The liquid collects in a separate container.
  • A Schlenk flask can be a round, pear-shaped or tubular bulb that stretches vertically into a long, thin neck with a side-arm. The side arm features a valve so that pressure or gas can be released from the flask.
  • Volumetric flasks are flasks used to measure specific volumes of material. They are generally gradated with metric markings to measure the volume of material in the container. They are typically composed of a round or pear-shaped bulb and a long thin neck topped by a stopper or rubber bung. Because they are generally used for measurement or reactions and not heating or boiling, they can be made of plastic or glass.

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