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Preferential discharge of cations during electrolysis

Description

This experiment shows that metal cations are preferentially discharged, in relation to the position of the metal in the reactivity series.

Type of Activity

:
class practical

Audience

:
Teacher

Age Group

:
14 to 18 years

Credits

:
This is an experiment from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.
preferential-discharge-of...



Apparatus Chemicals

Eye protection: goggles

Each working group requires:

Beaker (250 cm3)

Beaker (100 cm3), 2

Boiling tube

Test-tubes, 2 or 3

Teat pipette

Bunsen burner

Heat resistant mat

Tripod and gauze

Platinum electrodes, 1 cm square, with platinum leads sealed through glass tubes, both supported in a rubber bung or cork so that the electrodes are about 2 cm apart (Note 1), 2

DC power pack for supplying about 3–4 V

Light bulb (5 V) and holder

Several lengths of connecting wire, including two fitted with crocodile clips

Emery paper

Access to:

Copper(II) sulfate, about 0.5 M, 200 cm3

Iron(II) sulfate, about 0.5 M, 200 cm3

Zinc sulfate, about 0.5 M, 200 cm3 (IRRITANT, DANGEROUS FOR THE ENVIRONMENT)

Nitric acid, about 4 M (CORROSIVE), 20 cm3

Aqueous ammonia, about 4 M (IRRITANT), 10 cm3

Optional: Solution of mercury(II) chloride (VERY TOXIC) mixed with ammonium thiocyanate (HARMFUL) (Note 2)

Refer to Health & Safety and Technical notes section below for additional information.

 










This experiment shows that metal cations are preferentially discharged, in relation to the position of the metal in the reactivity series.

ADDITIONAL INFORMATION

This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany Practical Physics and Practical Biology.

The resource image was supplied by Science Photo Library / © Trevor Clifford Photography.