impact BH350, User Manual

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Explorer Pro
3.14 Density
Density determinations of solids and liquids can be made with the Explorer Pro Balance. The Explorer Pro Balance contains
built in reference density tables for water and ethanol at temperatures between 10 °C and 30 °C. It is not necessary to refer to any
external tables to calculate density.
3.14.1 Balance Preparation for Density Measurements
The Explorer
Pro
Balance is equipped with a weigh below hook which can be attached to the bottom of the balance. When
making density measurements, it is necessary to support the balance on both sides allowing enough clearance to for a beaker
to fit under the balance, a platform or laboratory jacks can be used. Remove the protective adhesive cap from the bottom of the
balance as shown in the figure below. Screw the weigh below hook into the bottom of the balance.
Q =
m
V
Density determinations are performed by using Archimedes' principle . This princple states that every solid body immersed in a
fluid loses weight by an amount equal to that of the fluid it displaces.
The density of a solid is determined with the aid of a liquid whose
density Q
0
is known (water or ethanol are usually used as
auxiliary liquids). The solid is weighed in air ( A ) and then in the auxiliary liquid ( B ). The density Q can be calculated from the
two weighings as follows:
Q
A
The balance allows direct determination of the buoyancy
P (
P = A - B) and consequently the above formula can be simplified:
A
P
Q = • Q
0
Q =
Density of the solid
A =
Weight of the solid in air
B =
Weight of the solid in the auxilary liquid
Q
0
= Density of the auxiliary liquid at a given temperature (this value depends on the temperature. The density
table is included in
Explorer
Pro
Balances).
P =
Buoyancy of the solid in the auxiliary liquid (corresponds to
A - B).
As previously mentioned, the balance contains built in density tables for water and and ethanol. In the the event that a different
liquid is to be used, provisions are made to enter the density of the desired liquid and enter its name into a library. The following
procedure uses water as an example.
A - B
• Q
0
3.14.2 Solid Density Determinations
The density Q is the quotient of the mass m and the volume V .
BOTTOM OF BALANCE
WEIGH BELOW
HOOK INSTALLATION
LOCATION
WEIGH BELOW
HOOK
BALANCE SUPPORT
PROTECTIVE
COVER
PLATE