Beaker (glassware)

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Beaker
Beakers of several sizes
Uses Liquid volume containment
and measurement
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.

Structure[edit]

(A) A low-form or Griffin form beaker (B) A tall-form or Berzelius beaker (C) A flat beaker or crystallizer

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 and are mostly used for titration.[4]

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.

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]

References[edit]

  1. ^ Oxford English Dictionary 1989 edition
  2. ^ a b c British Standard 6523 (1984) Glass beakers for ginal experiments use
  3. ^ A. I. Vogel (1974) Practical Organic Chemistry Third edition (Longman, London) page 46 ISBN 0-582-44245-1
  4. ^ a b Chemistry World August 2011 Classic kit: Griffin's Beaker

Further reading[edit]

  • ASTM E960 - 93 (2008) Standard Specification for Laboratory Glass Beakers