Flasks and flasks

Flasks and beutes are instruments, generally made of glass, that are used in chemistry as containers. There are different capacities of flasks, their shape can be spherical or conical, and the bottom flat. Flasks are also characterised by the long glass neck that starts with the spherical or conical body, and ends with the hermetic stopper.

These flasks are also characterised by the long glass neck that starts with the spherical or conical body, and ends with the hermetic stopper.

Finally, volumetric flasks are common, i.e. they contain a given volume of liquid at a given temperature. The capacity of the flasks is indicated by a notch on the neck of the device, called the 'calibration notch'. The most common capacities in which flasks are produced are from 50 ml to 1000 ml.

Use

Flasks are used for the preparation of solutions of known concentration. They are also used for precise dilutions in analytical chemistry.
A liquid is placed inside the apparatus via a funnel, taking care that this does not exceed the calibration mark. If drops were to be created above the calibration notch, these would add to the total below it, and an error could be made in the measurement of the liquid inserted.

Water and its solutions form a concave meniscus by adhering to the walls of the flask, due to surface tension. Mercury, on the other hand, forms a convex meniscus.
In order to obtain an accurate measurement, the liquid is inserted before the meniscus reaches the calibration mark, and is then brought up to level using a pipette and a dropper.

The liquid is then dispensed into the flask.

Bottles

The beute are a special type of flask, characterised by a truncated conical base and cylindrical neck. Compared to a traditional flask model, the flask has a thicker and shorter neck, as its walls rise up to it from the flat bottom. This special shape allows the liquid inside to be agitated without spilling it and without the risk of it escaping from the container. There are different capacities offlasks, generally ranging from 10 ml to 1 L.

The beutes are widely used in chemistry, being especially suitable due to their shape for titrations and recrystallisation. Nevertheless, flasks are not particularly suitable for accurate volumetric measurements. In fact, their measurements are accurate to within 5%.

Flasks are also used in microbiology for the preparation of microbial cultures. The use of minimal volumes of liquid, usually no more than one-fifth of the total volume of the flask, and baffles moulded into the inner surface of the container serve to maximise gas transfer and promote chaotic mixing when the flask is shaken.

These baffles are also used in microbiology.