A beaker is a generally cylindrical container with a flat bottom. 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.
Video Beaker (glassware)
Structure & common uses
Standard or "low-form" beakers typically have a height about 1.4 times the diameter. The common low form with a spout was devised by John Joseph Griffin and is therefore sometimes called a Griffin beaker. These are the most universal character and are used for various purposes--from preparing solutions and decanting supernatant fluids to holding waste fluids prior to disposal to performing simple reactions. In short, low form beakers are likely to be used in some way when performing just about any chemical experiment.
"Tall-form" (B) beakers have a height about twice their diameter. These are sometimes called Berzelius beakers and are mostly used for titration.
Flat beakers (C) are often called crystallizers because most are used to perform crystallization, but they are also often 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 straight rather than sloping sides. The exception to this definition is a slightly conical-sided beaker called a Philips beaker.
Maps Beaker (glassware)
Materials
Beakers are commonly made of glass (today usually borosilicate glass), 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
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. Most beakers are accurate to within ~10%.
The presence of a spout 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.
DIN EN ISO 3819:2015-12 defines the following types and sizes:
See also
- Beaker (drinkware)
- Beaker (archaeology)
- Beaker (disambiguation)
- Volumetric flask
- Stirring rod
- Test tube
- Graduated cylinder
- Scoop
References
Further reading
- ASTM E960 - 93 (2008) Standard Specification for Laboratory Glass Beakers
External links
- The dictionary definition of beaker at Wiktionary
- Media related to Beaker (glassware) at Wikimedia Commons
Source of article : Wikipedia
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