General Catalogue Chemistry - BECO Internacional LTDA.

667 320
Dewar flask
Silver finish, with protective casing, for
maintaining a constant temperature, e.g. in
calorific experiments.
Capacity: 500 ml
Diameter: 70 mm
Height: 210 mm
Weight: 1.0 kg
667 319
Dewar flask
Silver finish, with protective casing,
for experiments using the magnetic stirrer.
Capacity: 500 ml
Diameter: 70 mm
Height: 210 mm
Weight: 1.0 kg
667 321
Plastic lid
With stirrer and borehole for a thermometer, fits
the Dewar flasks (> 667 320 and
> 667 319). The lid serves as a holder for a
thermometer and reduces the exchange of
heat energy with the surroundings.
Diameter: 85 mm
Weight: 0.2 kg
All that is needed to conduct simple experiments
in calorimetry is an insulating flask (Dewar
flask) which reduces to a minimum the exchange
of thermal energy with the environment,
a plastic insert with a lid that holds the thermometer
and the stirrer used for manual agitation.
A magnetic stirrer may also be employed when
using the special, flat-bottomed version of the
Dewar flask.
Application examples for a calorimeter which is
assembled using > 667 321 along with
> 667 319 or > 667 320 include:
• Measuring the heat of solution
• Measuring the heat of neutralization
• Measuring the heat of reaction in solutions
Stoichiometry
The subject of stoichiometry deals with the
quantitative description of chemical reactions.
It is based on the realization that chemical elements
will react one with another only in certain,
constant proportions (law of constant proportions).
Consequently the final product of the
reaction - the chemical compound - always consists
of a constant share of the initial substances,
regardless of the quantities which were available.
Based on this fundamental law, conclusions can
be drawn regarding the relative masses of the
reactants involved, allowing us, for instance,
to calculate the yield factor for a reaction.
One of the elementary experiments in stoichiometry
is the quantitative synthesis of water, the
complement to the water analysis experiments
using Hofmann's electrolysis setup.
This experiment demonstrates that the reactants,
hydrogen and oxygen, join in a precise stoichiometric
ratio of 2:1 to form water (H2O). Gravimetric
examination of the water thus formed
allows us to derive information on the molar
mass of water.
The reaction vessel for stoichiometry also permits
the determination of the relative atomic
mass and the valence of metals.
668 802
Chemistry demonstration experiments
“General chemistry”
216 pages, DIN A 4
Demonstration experiments from the area of
general chemistry based on the Chemistry
Panel System. The equipement list of the
experiments also takes account of conventional
stand material
667 320
664 097
Stoichiometric reaction vessel
Metals react with water or acids in the stoichiometric
reaction vessel, developing hydrogen
while doing so. The atomic weight and the chemical
valence of the metal can be determined
on the basis of the volume of the gas collected
in a gas syringe and the preweighed metal
mass. The lower portion of the vessel is first
filled with water or acid, the vessel is then
purged with a non-reactive gas (N 2 ) and, after a
gas syringe has been attached to the reaction
vessel, the reaction is started by lowering the
plunger. The reaction then proceeds calmly,
without flames being produced.
Glass with lateral connection (GL 18) and
three-way stopcock at the lower end
Height: 225 mm
Diameter: 60 mm
Weight: 0.22 kg
analysis methods
Calorimetry
667 321
664 097
LEYBOLD DIDACTIC · GENERAL CATALOGUE CHEMISTRY
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