# Laboratory funnel

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{{Short description|Pipe with a wide top and narrow bottom}}
{{More citations needed|date=December 2021}}thumb|right|A Büchner funnel with a sintered glass disc

'''Laboratory funnels''' are made for chemical laboratory use. Many different kinds of [funnel](/source/funnel) have been designed for specialized applications. [Filter funnel](/source/Filter_funnel)s, [thistle funnel](/source/thistle_funnel)s (shaped like [thistle](/source/thistle) flowers), and [dropping funnel](/source/dropping_funnel)s have [stopcocks](/source/Stopcock) which allow the fluids to be added to a flask slowly. For solids, a powder funnel with a short and wide neck/stem is more appropriate as it prevents clogging.

When used with [filter paper](/source/filter_paper), filter funnels, [Buchner](/source/Buchner_funnel) and [Hirsch funnel](/source/Hirsch_funnel)s can be used to separate solid particles from a liquid by [filtration](/source/filtration). To separate very small particles the filter paper in the latter two may be replaced with a [sintered](/source/Sintering) [glass frit](/source/Fritted_glass).

[Separatory funnel](/source/Separatory_funnel)s are used in [liquid-liquid extraction](/source/liquid-liquid_extraction)s.

== Manufacturing ==

[Borosilicate glass](/source/Borosilicate_glass) is one of the most common materials of choice for laboratory applications as it is much less reactive than metals or plastics. However, plastic funnels made of non-reactive [polyethylene](/source/polyethylene) are used for transferring aqueous solutions. Plastic is most often used for powder funnels which do not come into contact with solvents in normal use.

==The types of funnels in the laboratory==

thumb|upright|A funnel for hot filtration
thumb|Two funnels, A - a simple stemmed funnel. B - a ground glass powder funnel
* '''[Plain funnels](/source/Funnels)''' are made in various dimensions, with longer or shorter necks.
* '''[Filter funnel](/source/Filter_funnel)s''' have a thin capillary tube neck, and ribs which speed up filtering.<ref name=boulder>{{cite web|url=https://www.colorado.edu/chembio|title=Chemistry and Biochemistry|date=6 September 2018|website=University of Colorado Boulder}}</ref>
* '''Powder funnels''' have a short, wide neck for fast pouring of powders.
* '''[Separatory funnel](/source/Separatory_funnel)s''' are pear-shaped, have a cap and a short neck, with a stopcock for the even pouring of fluids. These are used to decant two immiscible fluids. They can be graduated, though this is not very common. 
* '''[Hirsch funnel](/source/Hirsch_funnel)s''' are shaped much like normal funnels, but have holes or sintered glass at the base for quick filtration.
* '''[Dropping funnel](/source/Dropping_funnel)s''' are cylindrical, regularly graduated funnels with standard taper [ground glass joints](/source/ground_glass_joints). These are often supplied with a pressure equalizer.
* '''[Buchner funnel](/source/Buchner_funnel)s''' are  made of porcelain and include a plate of sintered glass or perforated porcelain. These are used in filtration under low pressure with a [Buchner flask](/source/Buchner_flask).<ref name=boulder/>
* '''Hot filtration funnel''' is a less usual funnel which is jacketed and surrounded by a heated fluid.<ref>{{cite web|url=https://www.erowid.org/archive/rhodium/chemistry/equipment/hot.filtration.html|title=An Efficient and Inexpensive Apparatus for Hot Filtration - [www.rhodium.ws]|website=www.erowid.org}}</ref>
* '''Eco funnel''' is equipped with a latching lid and gasket to reduce chemical contamination and conform to OSHA and EPA regulations.<ref>{{cite web|url=http://www1.udel.edu/ehs/waste/chemical-waste-funnel.html|title=Chemical Waste Funnels - Environmental Health & Safety - University of Delaware|website=Environmental Health & Safety}}</ref>

== References ==
{{Reflist}}

{{Laboratory equipment}}

Category:Laboratory glassware

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Adapted from the Wikipedia article [Laboratory funnel](https://en.wikipedia.org/wiki/Laboratory_funnel) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Laboratory_funnel?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.