Volumetric flask (measuring flask or graduated flask) is a piece of laboratory apparatus, a type of laboratory flask, calibrated to contain a precise volume at a certain temperature. Volumetric flasks are used for precise dilutions and preparation of standard solutions. 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 joint to accommodate a PTFE or glass stopper. The neck of volumetric flasks is elongated and narrow with an etched ring graduation marking. The marking indicates the volume of liquid contained when filled up to that point. The flask’s label also indicates the nominal volume, tolerance, precision class, relevant manufacturing standard and the manufacturer’s logo. Volumetric flasks are of various sizes, containing from 1 milliliter to 20 liters of liquid.
- Volumetric flasks are generally colorless but may be amber-colored for the handling of light-sensitive compounds such as silver nitrate or vitamin A.
- 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 beets.
- While conventional volumetric flasks have a single mark, industrial volumetric tests in analytical chemistry and food chemistry may employ specialized volumetric flasks with multiple marks to combine several accurately measured volumes.
- Volumetric flask is used to dilute original sample to known volume, so it is paramount that it contains exact volume. Burette is used to add titrant to the titrated solution and it has a scale on the side, so that you can precisely measure volume of the added solution.
- Volumetric apparatus is an essential requirement for quantitative estimations. Different types of glassware are used in quantitative chemistry to measure the volume of liquids. The reason why only glass equipment is used in chemistry is due to their negligible reactivity, high durability, and lesser costs