A Büchner flask, also known as a vacuum flask,The use of the term ''vacuum flask'' sometimes causes confusion with the

thermos flask A vacuum flask (also known as a Dewar flask, Dewar bottle or thermos) is an insulating storage vessel that slows the speed at which its contents change in temperature. It greatly lengthens the time over which its contents remain hotter or coo ...

filter flask, suction flask, side-arm flask, or Bunsen flask, is a thick-walled

Erlenmeyer flask An Erlenmeyer flask, also known as a conical flask (British English) or a titration flask, is a type of laboratory flask with a flat bottom, a conical body, and a cylindrical neck. It is named after the German chemist Emil Erlenmeyer (1825–190 ...

with a short glass tube and

hose barb Hose barbs are cylindrical pieces or parts for attaching and securing hoses. The barb-like rings on the cylindrical piece allow for an easy push-connection of flexible plastic or rubber tubing that is not easily disconnected. Hose barbs are use ...

protruding about 1-2 cm from its neck.

Description

The short tube and hose barb effectively act as an adapter over which the end of a thick-walled hose can be fitted to form a connection to the flask. The other end of the hose can be connected to source of

vacuum A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...

such as an

aspirator Aspirator may refer to: * Aspirator (medical device), a suction device used to remove bodily fluids from a patient * Aspirator (pump), a device producing vacuum by the Venturi effect in a constricted stream of fluid * Aspirator (entomology), also k ...

vacuum pump A vacuum pump is a type of pump device that draws gas particles from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke, and was preceded by the suction pump, which dates to ...

, or house vacuum. Preferably this is done through a trap (see below), which is designed to prevent the water to be sucked back from the aspirator into the Büchner flask. The purpose of applying a vacuum is to speed the filtration by providing a pressure differential across the filter medium that is greater than that produced by gravity alone.

Operation

The thick wall of the Büchner flask provides it the strength to withstand the pressure difference while holding a vacuum inside. It is primarily used together with a

Büchner funnel A Büchner funnel is a piece of laboratory equipment used in filtration. It is traditionally made of porcelain, but glass and plastic funnels are also available. On top of the funnel-shaped part there is a cylinder with a fritted glass disc/perf ...

fitted through a drilled

rubber bung A laboratory rubber stopper or a rubber bung or a rubber cork is mainly used in chemical laboratory, chemical laboratories in combination with Laboratory flask, flasks and test tube and also for Fermentation in winemaking, fermentation in winery. ...

or an elastomer adapter (a Büchner ring) at the neck on top of the flask for the

filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...

of samples. The Büchner funnel holds the sample isolated from the suction by a layer of

filter paper Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases. The raw materials are typically different pulp (paper), paper pulps. The pulp may be ...

. During filtration, the filtrate enters and is held by the flask while the residue remains on the filter paper in the funnel. The Büchner flask can also be used as a vacuum trap in a

vacuum line The Schlenk line (also vacuum gas manifold) is a commonly used chemistry apparatus developed by Wilhelm Schlenk. It consists of a dual manifold with several ports. One manifold is connected to a source of purified inert gas, while the other is c ...

to ensure that no fluids are carried over from the aspirator or vacuum pump (or other vacuum source) to the evacuated apparatus or vice versa.

Name

The flask is named after the

industrial chemist The chemical industry comprises the company, companies and other organizations that develop and produce industrial, specialty and other chemicals. Central to the modern world economy, the chemical industry converts raw materials (Petroleum, oil, ...

Ernst Büchner, who invented it, despite the mistaken belief held by many people that it is named after

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

and

Nobel Laureate The Nobel Prizes (, ) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make outstanding contributions in th ...

Eduard Buchner Eduard Buchner (; 20 May 1860 – 13 August 1917) was a German chemist and Zymurgy, zymologist, awarded the 1907 Nobel Prize in Chemistry for his work on fermentation (biochemistry), fermentation. Biography Early years Buchner was born in Mun ...

Notes

References

* {{DEFAULTSORT:Buchner Flask Laboratory glassware Air-free techniques