Conical Flask (Erlenmeyer flask) - Diagram, Definition, Types, Uses

Conical flask or Erlenmeyer flask is a laboratory flask with flat bottom, conical body and narrow neck.

It is used for mixing, heating, cooling and storing of liquid chemicals.

It was made by German chemist Emil Erlenmeyer in 1860.

The wide body and narrow neck helps in swirling of liquid without spilling.

The narrow neck also decreases evaporation and entry of dust or airborne materials. It can be closed with a stopper.

It is usually made up of borosilicate glass or plastic and is used in chemistry and biology laboratory.

Purposes of Conical Flask

The following are the purposes of conical flask-

Conical flask is used for mixing and swirling of solutions. The conical body and narrow neck helps in vigorous swirling without spilling.
It is used for titration experiments. The analyte can be swirled easily while titrant is added and the reaction or neutralization is observed.
It is used for heating and boiling liquids. The flat base gives stability during heating and the narrow neck decreases heat loss and evaporation of solvent.

It is used for storing and transferring samples. The narrow opening can be closed with rubber stopper, cork or screw cap.
It is used for culturing microorganisms. Culture media can be prepared and bacteria, yeast or algal cultures are grown in it. The shape helps in aeration and incubation.
It is used in filtration procedure. It collects liquid during filtration. Its modified form with thick wall and sidearm is used as Büchner flask or vacuum flask.

It is used in crystallization and recrystallization. The sloping wall and narrow neck decrease solvent evaporation and helps in controlled cooling.
It is used in solvent extraction. The design helps in vigorous mixing of immiscible liquids for separation and extraction of components.
It is used for cooling liquids. It is used in laboratory work where controlled cooling of solution is required.

Features of Conical Flask

The following are the features of conical flask-

Conical flask has a flat base, cone-shaped body and narrow cylindrical neck.
It prevents spilling of liquid during mixing. The sloped wall helps to swirl and mix liquid without spilling.
The narrow neck decreases evaporation of liquid. It also prevents dust and airborne contaminants from entering into the sample.

It has broad and flat bottom. This gives stability and the flask can stand properly on lab bench, hot plate or magnetic stirrer.
It is generally made up of borosilicate glass. It resists thermal shock and harsh chemicals. Sometimes plastic like polycarbonate or PETG is used when break resistance is needed.
It has volume markings on the side. These markings show approximate volume only and are not used for exact analytical measurement.

The narrow mouth can be closed easily with rubber stopper, cork, cotton plug or screw cap.
Many conical flasks have beaded rim at the top of the neck. It gives strength and protects the glass from chipping.
Some conical flasks have special modifications. Baffles are used for better aeration in cell culture. Sidearm is present in Büchner flask for vacuum filtration. Extra-wide base is present in Fernbach flask for more surface area.

Sizes Available of Conical Flask

The following are the sizes available of conical flask-

Conical flask is available in different capacities. It is generally found from 10 mL up to 6000 mL.
The small sizes are 10 mL, 25 mL, 50 mL and 100 mL.
The medium sizes are 125 mL, 150 mL, 200 mL, 250 mL, 300 mL and 500 mL.

The large sizes are 1000 mL, 2000 mL, 3000 mL, 4000 mL, 5000 mL and 6000 mL.
1000 mL flask is also called 1 litre flask. 2000 mL is 2 litres, 3000 mL is 3 litres, 4000 mL is 4 litres, 5000 mL is 5 litres and 6000 mL is 6 litres.
These flasks may also be grouped according to scale. 25-100 mL are small-scale flasks, 250-500 mL are medium-capacity flasks and 1000-5000 mL are large research flasks.

Maintenance of Conical Flask

The following are the maintenance of conical flask-

Conical flask should be rinsed immediately after each experiment. Distilled or deionized water is used for rinsing, mainly after use with acids or bases to prevent residue buildup.
The flask is washed gently with warm water and mild lab-grade detergent. Narrow neck brush or ultrasonic cleaner may be used. Abrasive powder and harsh brush are not used because they can scratch the inner glass surface.
The flask should be dried completely before storage. This prevents moisture buildup and contamination.

Flask should be checked before use. Chips, micro-cracks or scratches are observed carefully. Damaged flask should not be used because it can fail during heating or vacuum work.
Sudden temperature change should be avoided. Hot flask should not be placed directly on cold surface because thermal shock can break the glass.
Conical flask should be stored in upright position. It is kept in clean, dry and dust-free cabinet or on special racks to prevent accidental falling.

Flasks should be arranged according to size or calibration class. They are stored away from direct sunlight and corrosive chemicals.

Types of Conical Flasks

The following are the types of conical flasks-

Narrow neck flask
Narrow neck flask is the common and standard type of conical flask. It is used for titration, swirling of liquids without spilling and reducing evaporation.
Wide neck flask
Wide neck flask has a large opening at the top. It is used for easy addition of solid materials and stirring with glass rod.

Borosilicate glass flask
Borosilicate glass flask is the traditional type of conical flask. It is heat resistant, chemical resistant and used for boiling and autoclave sterilization.
Plastic flask
Plastic flask is a shatterproof type of conical flask. It is made up of polypropylene, polycarbonate or PETG and is used in cell culture, field work and teaching laboratory.
Screw-cap flask
Screw-cap flask has threaded top for fitting screw cap. It is used for safe storage and transport of samples.

Stoppered flask
Stoppered flask is made to hold glass stopper or rubber stopper. It is used for sealing and storing prepared solutions.
Baffled flask
Baffled flask has indentations at the bottom. It increases turbulence and oxygen exchange during shaking and is used for growing cell cultures.
Filtering flask or Büchner flask
Filtering flask or Büchner flask has thick and heavy wall with a sidearm. It is connected with vacuum hose and used in filtration procedure.

Fernbach flask
Fernbach flask has very broad base compared to its height. It gives large surface area and is used for maximum aeration in biological growth.
Culture flask
Culture flask is used for cell culture work. It is often pre-sterilized and has vented closure for gas exchange during incubation.
Graduated flask
Graduated flask has printed or etched scale markings. It is used for measuring approximate volume of liquid inside the flask.

Uses of Conical flask

The following are the uses of conical flask-

Conical flask is used for mixing and swirling of solutions. The slanted sides and narrow neck helps to swirl and mix liquids without spilling.
It is used for titration experiments. The solution can be swirled easily while titrant is added and the reaction is observed.
It is used for heating and boiling liquids. The flat base gives stability on hot plate or Bunsen burner and the narrow neck decreases loss of solvent by evaporation.

It is used for storing and transferring samples. The narrow opening can be closed with rubber stopper, cork or screw cap for temporary storage and transport of liquid samples.
It is used for culturing microorganisms. Culture media and suspensions of bacteria, yeast or algae are grown in it, mostly with shaking on orbital shaker.
It is used in filtration procedure. It collects filtrate in normal filtration and thick-walled vacuum form is used for rapid vacuum filtration.

It is used in crystallization and recrystallization. The sloped wall helps in controlled cooling, which is needed for purification of solid compounds or slow concentration of solutions.
It is used in solvent extraction. The flask can be closed and mixed strongly to separate and extract components from immiscible liquids.
It is used for cooling liquids. It is used in laboratory process where cooling or incubation of chemical solutions is required.

Advantages of Conical Flask

The following are the advantages of conical flask-

Conical flask helps in spill-free mixing. The tapered conical body and narrow neck helps to swirl and mix liquid strongly without splashing or spilling.
It reduces evaporation of liquid. The slanted wall helps hot vapour to condense and flow back into the liquid. The narrow neck also reduces exposure of liquid surface to air.
It has high stability. The broad and flat base gives low centre of gravity and the flask can stand safely on lab bench, hot plate or magnetic stirrer.

It is easy to seal and store. The small opening can be closed with rubber stopper, cork or screw cap and solution can be stored safely.
It prevents contamination. The narrow mouth decreases entry of dust and other airborne contaminants into the sample.
It gives even heating and cooling. The flat bottom makes stable contact with heat source and the conical shape helps in uniform heat distribution and controlled cooling.

It is safe and easy to handle. The cylindrical neck gives proper place to hold the flask by hand or to fix it with laboratory clamp.
It is durable and can be sterilized. Borosilicate glass conical flask can withstand sudden temperature change, harsh chemicals and heat sterilization in autoclave.

Limitations of Conical Flask

The following are the limitations of conical flask-

Conical flask is not used for exact volume measurement. It has graduated markings, but these are only approximate and usually within 5% accuracy.

It is difficult to clean properly. The narrow neck makes it hard to reach inside and clean, when compared with wide mouth vessels like beaker.
It has restricted access. The narrow opening does not allow easy insertion of pipettes, solid chemicals or measuring probes.
Standard conical flask is not safe for vacuum application. It does not have reinforced wall and may implode under reduced pressure, so thick-walled vacuum flask is used instead.

It is not suitable for high-energy reactions. The glass wall is usually thin and cannot safely contain high-energy chemical reactions.
It is more fragile and costly than simple laboratory beaker. It can break easily and needs careful handling.

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Conical Flask (Erlenmeyer flask) – Diagram, Definition, Types, Uses