picnómetro

A picnometer is a glass flask with a precisely known volume. It is used to determine the density of liquids and solids. The name "picnometer" comes from the Greek words "píknos" (dense) and "métron" (measure).

The principle behind the picnometer's operation relies on its precise volume. To determine the density of a liquid, the picnometer is first weighed empty. Then, it is filled with the liquid, ensuring no air bubbles are trapped, and weighed again. The difference in weight gives the mass of the liquid that occupies the known volume of the picnometer. Density is then calculated using the formula: density = mass / volume.

For determining the density of solids, a different approach is used. The picnometer is filled with a liquid of known density. The solid is then added to the picnometer, and the volume of the displaced liquid is measured. This volume corresponds to the volume of the solid. The mass of the solid can be determined by weighing it separately. With the mass and volume of the solid known, its density can be calculated.

Picnometers are essential tools in chemistry and physics laboratories for accurate density measurements. They are particularly useful for liquids and finely powdered solids where other methods might be less precise. The accuracy of a picnometer depends on the precision of its manufacturing and the care taken during its use.