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Determining density of liquids
The density of a fluid is determined with the help of a
volume [ V ]. The sinker is weighed in air [ A ] as well as in the sample fluid [ B ].
According to the Archimedes' Principle a body immersed in a fluid experiences a
force of buoyancy. [ G ]. This force equals the weight force of the fluid displaced by
the volume of the body.
The volume [ V ] of the immersed body equals the volume of the displaced fluid.
G = buoyancy of sinker
Buoyancy of sinker =
Weight of the sinker in air [ A ] - weight sinker in sample liquid [ B ]
From this follows:
ρ = density of sample fluid
A = weight of sinker in air
B = weight of sinker in sample fluid
V = volume of sinker*
*
If the volume of the sinker is unknown, this can be determined by a solid body
density measurement e.g. in water and be calculated as follows.
V = volume of sinker
A = weight of sinker in air
B = weight of sinker in water
ρ
= density of water
W
2.1
Influencing magnitudes and error sources
Air pressure
Temperature
Volume deviation of the sinker
Surface tension of the liquid
Air bubbles
Immersion depth of the sample dish of sinker
Porosity of the solid
6
sinker
A-B
ρ =
V
providing a known
ACS-A03-BA-e-1210
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