væskepyknometer

A væskepyknometer, or liquid pycnometer, is a precise laboratory instrument used to determine the density and specific gravity of liquids. It is essentially a glass flask of a known volume, designed to be filled with a liquid to a specific mark or to the brim. The accuracy of a pycnometer relies on its precisely manufactured volume and its ability to be filled reproducibly.

The principle behind its operation is straightforward. First, the empty, clean, and dry pycnometer is weighed. Then, it is filled with the liquid of interest, ensuring no air bubbles are trapped and that the liquid level reaches the designated fill line. Any excess liquid is carefully removed. The filled pyknometer is then weighed again. By subtracting the weight of the empty pyknometer from the weight of the filled pyknometer, the mass of the liquid is obtained.

Knowing the precisely calibrated volume of the pyknometer and the mass of the liquid it contains, the density of the liquid can be calculated using the formula: density = mass/volume. For accurate measurements, the pycnometer and the liquid should be at a stable, known temperature, as the volume of both the glass and the liquid changes with temperature. Specific gravity is then determined by comparing the density of the liquid to the density of a reference substance, typically water, at the same temperature. Pycnometers are crucial in fields requiring accurate liquid density measurements, such as chemistry, physics, and quality control.