A volumetric flask (measuring flask or graduated flask) is a piece of laboratory apparatus, a type of

laboratory flask Laboratory flasks are vessels or containers that fall into the category of laboratory equipment known as glassware. In laboratory and other scientific settings, they are usually referred to simply as flasks. Flasks come in a number of shapes an ...

, calibrated to contain a precise volume at a certain temperature. Volumetric flasks are used for precise dilutions and preparation of

standard solution In analytical chemistry, a standard solution (titrant or titrator) is a solution containing an accurately known concentration. Standard solutions are generally prepared by dissolving a solute of known mass into a solvent to a precise volume, or by ...

s. These flasks are usually pear-shaped, with a flat bottom, and made of glass or plastic. The flask's mouth is either furnished with a plastic snap/screw cap or fitted with a

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to accommodate a

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or glass stopper. The neck of volumetric flasks is elongated and narrow with an etched ring

graduation A graduation is the awarding of a diploma by an educational institution. It may also refer to the ceremony that is associated with it, which can also be called Commencement speech, commencement, Congregation (university), congregation, Convocat ...

marking. The marking indicates the volume of liquid contained when filled up to that point. The marking is typically

calibrated In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...

"to contain" (marked "TC" or "IN") at 20 °C and indicated correspondingly on a label. The flask's label also indicates the nominal

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

, tolerance, precision class, relevant manufacturing standard and the manufacturer's logo. Volumetric flasks are of various sizes, containing from a fraction of a milliliter to hundreds of liters of liquid.

Classes

Calibration and toleration standards for volumetric flasks are defined in the following standard specifications and practices:

ASTM ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...

E288, E542, E694,

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

1042, and

GOST GOST () refers to a set of international technical standards maintained by the Euro-Asian Council for Standardization, Metrology and Certification (EASC), a regional standards organization operating under the auspices of the Commonwealth of I ...

1770-74. According to these specifications, volumetric flasks come in two different classes. The higher standard flasks (Class A, Class 1, USP or equivalent depending on the country) are made with a more accurately placed graduation mark, and have a unique serial number for traceability. Where this is not required, a lower standard (Class B or equivalent) is used for qualitative or educational work.

Modifications

Volumetric flasks are generally colourless but may be amber-coloured for the handling of light-sensitive compounds such as

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. A modification of the volumetric flask exists for dealing with large quantities of solids that are to be transferred into a volumetric vessel for dissolution. Such a flask has a wide mouth and is known as a ''Kohlrausch volumetric flask''. This kind of volumetric flask is commonly used in analysis of the sugar content in

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s. While conventional volumetric flasks have a single mark, industrial volumetric tests in

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and

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may employ specialized volumetric flasks with multiple marks to combine several accurately measured volumes. A highly specialized kind of the volumetric flask is the ''Le Chatelier flask'' for use with the volumetric procedure in

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

determination.

Classes

Modifications

See also

References

Further reading