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An oscillating reaction

Description

This is one of the simplest oscillating reactions to demonstrate. Bromate ions oxidise malonic acid to carbon dioxide. The reaction is catalysed by manganese(II) ions. The reaction mixture oscillates in colour between red-brown and colourless with a time period of about 20 seconds.

Type of Activity

:
demonstration

Audience

:
Teacher

Age Group

:
14 to 18 years

Credits

:
This resource has been provided by, or developed in partnership with, Nuffield Foundation
an-oscillating-reaction



Apparatus Chemicals

For each demonstration:

Eye protection: goggles

Disposable gloves (preferably nitrile) - optional

Beaker (1 dm3)

Magnetic stirrer (optional: Note 1)

Weighing boats or watch-glasses, 3

Balance, reading to 0.1 g

Concentrated sulfuric(VI) acid (CORROSIVE), 75 cm3

Propane-1,3-dioic (malonic) acid (HARMFUL), 9 g

Potassium bromate(V) (TOXIC, OXIDISING), 8 g

Manganese(II) sulfate-1-water (HARMFUL, DANGEROUS FOR THE ENVIRONMENT), 1.8 g

Deionised or distilled water, 750 cm3

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

 








Page last updated October 2015

This is one of the simplest oscillating reactions to demonstrate. Bromate ions oxidise malonic acid to carbon dioxide. The reaction is catalysed by manganese(II) ions. The reaction mixture oscillates in colour between red-brown and colourless with a time period of about 20 seconds.

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