Beaker (glassware)
 Beakers of several sizes |
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| Uses | Liquid volume containment and measurement |
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| Related items | Laboratory flask |
A beaker is a simple container for stirring, mixing and heating liquids commonly used in many laboratories. Beakers are generally cylindrical in shape, with a flat bottom.[1] Most also have a small spout (or "beak") to aid pouring as shown in the picture. Beakers are available in a wide range of sizes, from one millilitre up to several litres.
Contents |
Structure [edit]
Standard or "Low-form" beakers typically have a height about 1.4 times the diameter.[2] The common low form with a spout was devised by John Joseph Griffin and is therefore sometimes called a Griffin beaker.[3][4] These are the most universal character and are used for various purposes - from preparing solutions and decanting supernatant fluids to simple reactions.
"Tall-form" (B) beakers have a height about twice the diameter.[2] These are sometimes called Berzelius beakers.[4] They are mostly used for titration.
Flat beakers (C) are often called crystallizers, because most are used to perform crystallization, but often it is also used as a vessel for use in hot-bath heating. These beakers usually do not have a flat scale.
A beaker is distinguished from a flask by having sides which are straight rather than sloping. The exception to this definition is a slightly conical sided beaker called a Phillips beaker.
Materials [edit]
Beakers are commonly made of glass (today usually borosilicate glass[2]), but can also be in metal (such as stainless steel or aluminium) or certain plastics (notably polythene, polypropylene, PTFE). A common use for polypropylene beakers is gamma spectral analysis of liquid and solid samples.
Shape [edit]
Beakers are often graduated, that is, marked on the side with lines indicating the volume contained. For instance, a 250 mL beaker might be marked with lines to indicate 50, 100, 150, 200, and 250 mL of volume. These marks are not intended for obtaining a precise measurement of volume (a graduated cylinder or a volumetric flask would be a more appropriate instrument for such a task), but rather an estimation.
The presence of a lip means that the beaker cannot have a lid. However, when in use, beakers may be covered by a watch glass to prevent contamination or loss of the contents, but allowing venting via the spout. Alternatively, a beaker may be covered with another larger beaker that has been inverted, though a watch glass is preferable.
See also [edit]
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Look up beaker in Wiktionary, the free dictionary. |
- Beaker (drinkware)
- Beaker (archaeology)
- Beaker (disambiguation)
- Volumetric flask
- Stirring rod
- Test tube
- Graduated cylinder
- Scoop
References [edit]
- ^ Oxford English Dictionary 1989 edition
- ^ a b c British Standard 6523 (1984) Glass beakers for ginal experiments use
- ^ A. I. Vogel (1974) Practical Organic Chemistry Third edition (Longman, London) page 46 ISBN 0-582-44245-1
- ^ a b Chemistry World August 2011 Classic kit: Griffin's Beaker
Further reading [edit]
- ASTM E960 - 93 (2008) Standard Specification for Laboratory Glass Beakers
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