U14331 [1002898]

U14331 [1002898]
®
3B SCIENTIFIC
SCIENTIFIC® PHYSICS
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Daniell cell U14331
Instruction sheet
8/05 ALF
1
2
1 Copper electrode with 4-mm plug
2 Clay cylinder
3 Zinc electrode with 4-mm plug
4 Glass vessel
3
4
• The apparatus must be thoroughly cleaned after the
experiment.
• Current regulations must be strictly adhered to when
disposing of the chemicals.
The Daniell cell is used for investigating the properties of
an electrochemical cell.
1. Safety instructions
• Caution! Heavy metal salts are toxic.
• Safety goggles are a must when working with acids or
bases.
• Students must always be thoroughly informed about
the hazards of the chemicals used.
• Leaking fluid can cause permanent stains and holes
in clothing.
2. Description, technical data
The Daniell cell, named after John Frederic Daniell, is a
galvanic cell consisting of two cylindrical electrodes (zinc
and copper) in a glass vessel. The electrodes are separated from one another by a clay cylinder.
3
Dimensions:
Connections:
Appropriate filling:
105 mm high, 65 mm Ø
via 4-mm plugs
Copper sulphate solution (CuSO4),
10%,
Zinc sulphate solution (ZnSO4), 10%
Reduction:
Cu2+ + 2e− → Cu
Redox reaction:
Zn+ Cu2+ → Zn2+ + Cu
Theoretically, the Daniell cell provides a current of 1.1 V.
However, the measured reading, as a rule, is always slightly
below the theoretical value.
2.1 Scope of delivery
1 Glass vessel
1 Clay cylinder
1 Copper electrode with plug
1 Zinc electrode with plug
4. Operation
3. Theory
The combination of two half-cells for the purpose of
converting chemical energy into electrical energy is called
a galvanic cell. In a Daniell cell, a copper electrode with a
copper sulphate solution is situated in one half-cell and
a zinc electrode with a zinc sulphate solution is found in
the second. In galvanic cells, the baser metal of the two
always forms the negative pole. In this case, the electrons thus flow from zinc to copper. The zinc electrode is
dissolved over a period of time, while metal copper settles on the copper rod. The inner conduction is carried
out by the negative sulphate ions which can pass the
wall of the clay cylinder. Current drain is completed either when the zinc electrode is dissolved or when the
copper sulphate solution has been used up. The following reactions can be appreciated:
Oxidation:
Zn → Zn2+ + 2e −
• Before the start of the experiment, prepare a sufficient amount of the electrolyte solutions.
• For preparing one litre of 1-molar copper sulphate
solution, take 249.5 g CuSO4 and add distilled water
till you get one litre of solution.
• For preparing one litre of 1-molar zinc sulphate solution, take 287.4 g ZnSO4 and add distilled water till
you get one litre of solution.
• For preparing a 0.1-molar solution, only take 1/10th of
the specified quantities.
• Pour the solutions into the corresponding half-cells.
• Measure the current generated with a voltmeter.
• The experiment can also be repeated with a 1-molar
copper sulphate and zinc sulphate solution.
• The apparatus and electrodes must be thoroughly
cleaned immediately after the experiment.
• Chemicals which cannot be reused must be stored in
special vessels and disposed of in an orderly fashion
afterwards, strictly adhering to current regulations.
1 Zinc sulphate (ZnSO )
4
solution
2 Porous partition
3 Copper sulphate (CuSO )
4
solution
1
3
2
Fig. 1: Daniell-Element
3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany4• www.3bscientific.com • Technical specifications subject to change
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