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Density determination kit for Excellence XP/XS analytical balances
6
3
Principle of the density determination
The density ρ is the quotient of the mass m and the volume V .
m
ρ
=
V
The international system of units specifies kg/m
better suited to lab purposes.
Density determinations are frequently performed by Archimedes' principle, which is also used with
the density determination kit for the balances. This principle states that every solid body immersed in
a fluid apparently loses weight by an amount equal to that of the fluid it displaces.
The procedure for the density determination by Archimedes' principle depends on whether the density
of solids or liquids has to be determined.
4
Density determination of solids
4.1
Fundamentals
The density of a solid is determined with the aid of a liquid whose density ρ
are usually used as auxiliary liquids). The solid is weighed in air (A) and then in the auxiliary liquid
(B). The density ρ can be calculated from the two weighings as follows:
A
ρ
Density:
=
A-B
A-B
α
V
Volume:
=
ρ
0
4.
Performing the density determination
Note: These instructions explain how to work with the density determination kit. They describe the
procedure for performing a density determination manually.
If you need information about operating your XP/XS balance, please refer to the Operating Instructions
which you received with the balance. The Operating Instructions include instructions for working with
the density determination software which is built into the XP/XS balance.
- ρ
)+ ρ
(ρ
0
L
L
- ρ
L
as the unit of density. However, the unit g/cm
3
ρ = Density of sample
A = Weight of sample in air
B = Weight of sample in the auxiliary liquid
ρ
= Density of the auxiliary liquid
0
ρ
= Air density (0.0012 g/cm
L
α = Balance correction factor (0.99985), takes air
buoyancy of the adjustment weight into account.
is known (water or ethanol
0
)
3
is
3
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