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Turning copper coins into 'silver' and 'gold'

Description

A ‘copper’ coin is dipped into a solution of sodium zincate in contact with zinc. The coin is plated with zinc and appears silver in colour. The plated coin is held in a Bunsen flame for a few seconds and the zinc and copper form an alloy of brass. The coin now appears gold.

Type of Activity

:
demonstration

Audience

:
Teacher

Age Group

:
11 to 18 years

Credits

:
This is an experiment from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.
turning-copper-coins-into...



Apparatus Chemicals

For each demonstration:

Eye protection: goggles

Disposable gloves (preferably nitrile)

Beaker (250 cm3)

Bunsen burner (Note 1)

Tripod and gauze

Pair of tongs or forceps

Glass stirring rod

Access to a top-pan balance

Sodium hydroxide pellets (CORROSIVE), 24 g

Zinc powder (HIGHLY FLAMMABLE, DANGEROUS FOR THE ENVIRONMENT), 5 g

Steel wool (Note 2)

Deionised or distilled water, 100 cm3

Copper coins (Note 3)

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

 







Page last updated October 2015

A ‘copper’ coin is dipped into a solution of sodium zincate in contact with zinc. The coin is plated with zinc and appears silver in colour. The plated coin is held in a Bunsen flame for a few seconds and the zinc and copper form an alloy of brass. The coin now appears gold.

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 experiment is also part of the Royal Society of Chemistry's Continuing Professional Development course: Chemistry for non-specialists