ERLENMEYER FLASK: CHARACTERISTICS, USES, METHODS OF USE - CHEMISTRY - 2025

The Erlenmeyer flask is a glass material characterized by its conical shape and for being widely used in laboratories of chemistry, biology, pharmacy and other disciplines. In some countries it is known as a fiola, and it represents by itself an icon of scientific experimentation with regard to chemical reactions.

It appeared for the first time in 1861, being one of the many contributions to the world of chemistry of the German chemist Richard August Carl Emil Erlenmeyer. Its narrow neck is ergonomic, facilitating its shaking and handling during volumetric titrations.

Erlenmeyer flasks. Source: Bongoman via Wikipedia.

Above is a set of Erlenmeyer flasks, whose volumes and designs may vary slightly, but keep the conical shape constant. They are, along with beakers, one of the most valued glass materials, due to their versatility and the ability to be sealed by corks, aluminum foil and cellophane, rubber bands or lids, etc.

How they are used will greatly depend on the methods or analyzes for which they are intended. They are used to carry out chemical reactions, to store liquids or phases, and also as containers for heating and mixing without appreciable losses due to evaporation or splashing.

characteristics

Volumes for Erlenmeyer flasks range from 50 mL to 6,000 mL. Normally those with a volume greater than 1 liter are used for the preparation of dissolution media or mobile phases (liquid chromatography).

However, all of them are conical, with narrow and cylindrical necks, flat and transparent bases, and their walls can come graduated or be provided with labels that allow them to be labeled. These graduations are rarely overly relied upon, as more accurate materials are available for volume measurements, such as graduated cylinders or pipettes.

The Erlenmeyer flask neck presents the convenience that it can be closed hermetically thanks to its frosted, or it has edges that allow it to be screwed on by countless caps. Its height can vary between different flasks, although it is almost always short so that the liquid falls quickly to the base of the bottom.

The narrow mouth favors and ensures the pouring of liquids without so much spillage, as well as avoiding that the vapors tend to escape due to its reduced cross-sectional area as they first condense on the neck of the flask.

Applications

Volumetric titrations

Erlenmeyer flasks find one of their most characteristic uses in titration or volumetric titrations.

This is because its flat and wide bottom allows the analyst to observe the color of the solution they are titrating while stirring it. And even more, on a white paper it simplifies the visual detection of the end point; that is, the turning or color change of the indicator solution that indicates when the titration was completed.

These flasks in analytical chemistry laboratories are synonymous with titrations, and in teaching they are taught how to shake them correctly (with a flick of the wrist) while adding drops of the titrant located in the burette. Its base is also easy to cover with aluminum foil in the case of sensitive reactions to sunlight.

Mixing container

Erlenmeyer flasks are very useful for mixing solvents or reagents.

Solvents

When it comes to solvents, the purpose is usually to prepare dissolution media or mobile phases. With the help of a magnetic stirrer, the solvents are poured through its neck, using a funnel or not, and then mixed without the risk of splashing due to the narrowness of its neck and the height of the sloping walls.

Some dissolution media can demand large volumes, for which flasks of 1 liter or more are necessary. Properly covered, either with lids, cottons, corks, rubber bands, or aluminum foil, these are stored for a period of up to three months.

The mobile phases are identified thanks to a label that can be placed on one of the faces of the flask; its volumetric proportions of solvents used in its preparation. For example, 100: 20 means that 100 mL of water was used with 20 of methanol for the prepared mobile phase H ₂ O: CH ₃ OH.

It is here that Erlenmeyer flasks have also been used for culinary purposes. Although they are unconventional uses, they can be used to store lemonades, coffee, chalk, alcoholic beverages, etc.

Reagents

When it comes to reagents, chemical reactions are carried out, just like volumetric titrations. Said reaction mixture can be mixed and heated at the same time without the risk, again, of splashing or the release of many undesirable vapors.

Recrystallizations

A funnel can be incorporated into the neck of the Erlenmeyer flasks, inside which it has a filter paper through which a hot solution will pass through. Before this, however, it is recommended that the bottom of the flask is also hot to prevent the crystallization of the desired and dissolved substance from being premature.

Once the solution is filtered, the flask is stoppered and the crystals are allowed to mature while the temperature is slowly lowered. Thus, thanks to this technique, crystals of considerable purity are obtained for a specific analyte or product. This recrystallization is repeated as many times as necessary until the crystals are very pure.

Microbiology

Because of the ease with which these flasks are stoppered, anaerobic conditions can be recreated for the cultivation of microorganisms.

Methods of use

The methods for using the Erlenmeyer flask depend on the technique and the analysis being performed.

For example, for the titrations these should be held by their necks using the index, middle and thumb fingers, while moving the wrist as if drawing circles with the base of the flask.

If the flask is being magnetically stirred, it may be advisable to hold it with a clamp on a universal stand while adding all the reagents or heating the mixture.

Although its glass is resistant, the flask should always be handled with care not to hit its base, much less its mouth or neck; this worse affects the flasks or volumetric flasks with which solutions are prepared.

And with regard to cleaning, unless the solvent to be used is not water, it will also depend on what mixtures or reactions were carried out within them.

Finally, they can be dried with a little acetone, or by heating them in a muffle; since, after all, the least they are used for is for direct volume measurement (heat decalibration).

References

1. Whitten, Davis, Peck & Stanley. (2008). Chemistry (8th ed.). CENGAGE Learning.
2. Wikipedia. (2019). Erlenmeyer flask. Recovered from: en.wikipedia.org
3. John Williams. (2019). Erlenmeyer Flask: Function & Dimensions Video. Study. Recovered from: study.com
4. Thomas Publishing Company. (2019). Laboratory Glassware: Types of Laboratory Flasks. Recovered from: thomasnet.com
5. Helmenstine, Anne Marie, Ph.D. (September 13, 2019). Chemistry Glassware Names and Uses. Recovered from: thoughtco.com
6. Anne Davis. (December 28, 2018). What Is the Difference Between an Erlenmeyer Flask & a Beaker? Recovered from: careertrend.com
7. Sella Andrea. (June 30, 2008). Classic Kit: Erlenmeyer flask. Royal Society of Chemistry. Recovered from: chemistryworld.com