A volumetric flask (measuring flask or graduated flask) is a piece of

laboratory apparatus A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicia ...

, 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 and ...

, 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 is a solution containing a precisely known concentration of an element or a substance. A known mass of solute is dissolved to make a specific volume. It is prepared using a standard substance, such as a p ...

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

PTFE Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemour ...

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

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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 a ...

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

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volume Volume is a measure of occupied 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). The de ...

, 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 an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...

E288, E542, E694,

ISO ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Iso ...

1042, and

GOST GOST (russian: ГОСТ) refers to a set of International standard, international Technical standard, technical Standardization, standards maintained by the ''Euro-Asian Council for Standardization, Metrology and Certification (EASC)'', a region ...

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

silver nitrate Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic' ...

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...

. 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 known as a ''Kohlrausch volumetric flask''. This kind of volumetric flask is commonly used in analysis of the sugar content in

sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and which is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together wi ...

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

analytical chemistry Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separati ...

and

food chemistry Food chemistry is the study of chemical processes and interactions of all biological and non-biological components of foods. The biological substances include such items as meat, poultry, lettuce, beer, milk as examples. It is similar to biochemist ...

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, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

determination.

Classes

Modifications

See also

References

See also