The density of a liquid is determined from the buoyancy of the plummet, which has
a defined volume
G
ρ (fl) =
V
where:
ρ = specific gravity of a solid
ρ (fl) = density of the liquid
W (a) = weight of the solid in air
W (fl) = weight of the solid in liquid
G = buoyancy of the plummet
V = volume of the solid
Allowance Factors
You must allow for the following when determining the specific gravity of solids:
– the air buoyancy that affects the sample weighed in air
where ρ (a) = 0.0012 g/cm
3
= density of air under standard conditions
(temperature 20°C, pressure 101.325 kPa);
which results in the following:
W (a) · [ρ (fl) – ρ (a)]
ρ =+ ρ (a)
W (a) – W (fl)
– the immersion of the wires of the sample holder or sieve
When using this specific gravity determination kit, you must multiply the buoyancy
G = [W (a) – W (fl)] by the factor 0.99983 (Corr).
Therefore:
W (a) · [ρ (fl) – ρ (a)]
ρ =+ ρ (a)
[W (a) – W (fl)] · Korr
This factor allows for the buoyancy of the wires which are submerged deeper
when the sample is in the sample holder.
How this allowance factor is derived:
The buoyancy caused by the submerged wires depends on the height “h” by which
the liquid rises when the sample is immersed.
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