Volumetric Flasks
Volumetric flasks are vessels calibrated to contain and measure a precise amount of liquid at a certain temperature. They have a volume marking, may have a closure, and can be used to prepare dilutions and standards. Typically they are pear-shaped with a flat bottom and made of glass or plastic.
The flasks’ elongated and narrow necks have a single etched ring graduation mark that indicates the volume contained when the flask is filled to that point. This means the flask is calibrated "to contain." The flask markings also indicate the nominal volume, tolerance, precision class, manufacturing standard, and the manufacturer's logo.
Sizes for volumetric flasks range from 1mL to 20L. Smaller or micro flasks may have a large base for greater stability. A volumetric flask may have a plastic snap or screw cap or a ground glass joint to accommodate a glass stopper.
Two classes of volumetric flasks are available.
- The higher standard is Class A, Class 1, USP or equivalent; these are more accurate and have a unique serial number for traceability
- A lower standard is Class B or equivalent, which is suitable for qualitative or educational use
Volumetric flasks are generally clear or colorless but may be colored or coated for handling light-sensitive compounds.
The Kohlrausch volumetric flask is modified to help transfer large amounts of solids into the flask for dissolution; it is commonly used to measure the sugar content of sugar beets.
The Le Chatelier flask is designed for specific gravity determinations.