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Catalysis of a reaction between sodium thiosulfate and iron(III) nitrate solutions

Description

In this experiment the speed of a reaction is measured. Various metals in solution are tested as possible catalysts.

Credits

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

Eye protection

Stopclock or timer

Dropping pipette. Use the type of teat pipette usually fitted to Universal indicator bottles that does not allow squirting

Glass measuring cylinder (100 cm3)

Measuring cylinder (50 cm3)

Access to 0.1 M solutions of the following (Note 1):

Cobalt(II) chloride solution, (TOXIC), drops

Copper(II) sulfate solution, drops

Iron(II) sulfate solution, drops

Iron(III) nitrate solution, 250 cm3

Sodium thiosulfate solution, 250 cm3

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

 




Initially the iron(III) and thiosulfate ions form an unstable complex (which is dark-violet in colour):

Fe3+(aq) + 2S2O32-(aq)→ [Fe(S2O3)2(H2O)2]-(aq)

Over time the complex is consumed as thiosulfate (acting as a reducing agent) reduces iron(III) to iron(II) ions. Transition metal ions can catalyse this reduction process at different rates.




Page last updated October 2015

In this experiment the speed of a reaction is measured. Various metals in solution are tested as possible catalysts.

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.