where Do is the object’s density, Dw is the density of the calibration weight, and
0.0012 is the density of air under normal laboratory conditions (all densities are in
units of g/cm3). Clearly the greater the difference between Do and Dw the more serious
the error in the object’s measured weight.
The buoyancy correction for a solid is small, and frequently ignored. It may be
significant, however, for liquids and gases of low density. This is particularly important
when calibrating glassware. For example, a volumetric pipet is calibrated by
carefully filling the pipet with water to its calibration mark, dispensing the water
into a tared beaker and determining the mass of water transferred. After correcting
for the buoyancy of air, the density of water is used to calculate the volume of water
dispensed by the pipet.
EXAMPLE