Pycnometers and scale work hand in hand. A pycnometer is a tool that measures the volume of an object while a scale measures an object’s mass. Dividing mass by the volume yields the figure for the object’s density.
Why we need to know?
- Density determination of liquids by pycnometer
Density determination by pycnometer is a very precise method. It uses a working liquid with well-known density, such as water. We will use distilled water, for which temperature dependent values of density ρH2O are shown in Table 1. The pycnometer is a glass flask with a close-fitting ground glass stopper with a capillary hole through it. This fine hole releases a spare liquid after closing a top-filled pycnometer and allows for obtaining a given volume of measured and/or working liquid with a high accuracy.
Density determination of solid matter by pycnometer
Pycnometer can be also used to determine the density of homogeneous solid object that does not dissolve in working liquid (water). First, we need to measure the weight of pycnometer together with inserted object m0+mS. We add water and determine the weight mH2O′ (measured weight minus m0+mS). The volume of added water VH2O′ can be obtained as.