View source for Burette

[[Image:burette.svg|thumb|right|60px|diagram of modern burette]] 

A '''burette''' (also '''buret''') is a vertical cylindrical piece of [[laboratory glassware]] with a volumetric graduation on its full length and a precision tap, or [[stopcock]], on the bottom. It is used to dispense known amounts of a [[liquid]] [[reagent]] in [[experiments]] for which such [[precision]] is necessary, such as a [[titration]] experiment. Burettes are extremely accurate: class A burettes are accurate to ±0.05 cm<sup>3</sup>.

==Using a burette==
The precision of a burette makes careful measurement with a burette very important to avoid [[systematic error]]. When reading a burette, the viewer's eyes must be at the level of the graduation to avoid [[parallax]] error. Even the thickness of the lines printed on the burette matters; the bottom of the [[meniscus]] of the liquid should be touching the top of the line you wish to measure from. A common rule of thumb is to add 0.02 mL if the bottom of the meniscus is touching the bottom of the line. Due to the precision of the burette, even a single drop of liquid hanging from the bottom of a burette should be transferred to the receiving flask, usually by touching the drop to the side of the receiving flask and washing into the solution with the experimental [[solvent]] (usually water). Through careful control of the stopcock and rinsing, even partial drops of liquid can be added to the receiving flask.

==History==

The history of the burette parallels the history of volumetric analysis. Francois Antoine Henri Descroizilles developed the first burette (which looked more like a graduated cylinder) in 1791. [[Joseph Louis Gay-Lussac]] developed an improved version of the burette that included a side arm, and coined the terms "pipette" and "burette" in an 1824 paper on the standarization of indigo solutions. A major breakthrough in the methodology and popularization of volumetric analysis was achieved by [[Karl Friedrich Mohr]], who redesigned the burette by placing a clamp and a tip at the bottom.<ref>Louis Rosenfeld. ''Four Centuries of Clinical Chemistry''. CRC Press, 1999, p. 72-75.</ref>

[[Image:Gay-lussac burette.jpg|thumb|left|70px|Gay-Lussac burette]][[Image:Mohr burette.jpg|thumb|none|220px|Mohr burette]]

==References==
{{reflist|2}}

==External links==
*[http://www.dartmouth.edu/~chemlab/techniques/buret.html Using a Burette] from ChemLab at Dartmouth College
*http://core.ecu.edu/chem/chemlab/equipment/images/burette.jpg
*[http://chemed.chem.purdue.edu/genchem/lab/equipment/buret/use.html Use of the Buret]

{{Laboratory equipment}}

[[Category:Laboratory glassware]]
[[Category:Volumetric instruments]]


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