# Determine the volume of the pycnometer

Most of the pycnometers have a given volume. This volume can change with the time and temperature and therefore needs to needs to be determined precisely for accurate density measurements.

The exact volume of a pycnometer can be determined with two weighing's, on empty( in air) and one with water.

weight the empty pycnometer and write down the mass(filled with air)= 31.3910gm

Then fill the pycnometer with ultra pure water and put the pycnometer into water bath to 250 wait until pycnometer with water has stabilized to the temperature of the water bath. Typical stabilization time is 30 minutes.

If the capillary is not completely full add some water, wipe of the water on the pycnometer with paper towel.

Write down the mass of the pycnometer ( filled with ultra pure water) = 82.2415gm

Density of water at
250C =0.33704

Density of Air at 250C =0.001152

Then

This volume of 51.061 cm3 will be used for the exact measurement of the density of the sample with this pycnometer