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The equilibrium between two coloured cobalt species

Description

The equilibrium between cobalt species Co(H2O)62+ and CoCl42− can be disturbed by changing the chloride ion concentration or by changing the temperature. The colour changes accompanying the changes in equilibrium position are as predicted by Le Chatelier’s principle.

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Apparatus Chemicals

Eye protection

Reaction vessel, 1 or more (Note 1)

Rubber stopper or plastic cap (to fit the reaction vessel)

Beaker (250 cm3), 1 for each alcohol used

Wooden splints, as needed (Note 2)

Meter rule

The quantities of chemicals given are for one demonstration:

Cobalt(II) chloride-6-water (TOXIC, DANGEROUS FOR THE ENVIRONMENT), 4.0 g

Concentrated hydrochloric acid (CORROSIVE), 100 cm3

Crushed ice, about 200 cm3

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

 









Page last updated October 2015

The equilibrium between cobalt species Co(H2O)62+ and CoCl42− can be disturbed by changing the chloride ion concentration or by changing the temperature. The colour changes accompanying the changes in equilibrium position are as predicted by Le Chatelier’s principle.

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 .