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Halogen reactions with iron wool

Description

In this demonstration iron wool is heated with a bunsen flame in the presence of chlorine gas and the vapours of bromine and iodine. An exothermic redox reaction occurs which gives iron(III) halides as coloured solids. The vigour of the reaction depends on the reactivity order of the halogens.

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.
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Apparatus Chemicals

Eye protection for teacher and students, protective gloves for teacher

Access to a fume cupboard

Apparatus to set up a chlorine generator

Boiling-tubes, 2

Reduction tube (Note 1)

Beakers (100 cm3), 3

Tweezers

Teat pipette (preferably glass, with a narrow tip)

Test-tubes, 3 small, and a test-tube rack

Bunsen burner and heat-proof mat

Bosses, clamps and stands

The approximate quantities of chemicals below are sufficient for one demonstration:

Iron wool, 3 tufts about 1 g mass each (Note 2)

Hexane (HIGHLY FLAMMABLE, HARMFUL), 100 cm3(Note 2)

Liquid bromine (VERY TOXIC, CORROSIVE), 0.5 cm3

Sodium thiosulfate solution, 1 M, 500 cm3

Iodine solid (HARMFUL), 0.5 g

Silver nitrate solution, approximately 0.1 M, 10 cm3

To generate chlorine:

Sodium chlorate(I) solution (sodium hypochlorite), 10-14% (w/v) (CORROSIVE), fresh (Note 3)

Hydrochloric acid, 5M (IRRITANT AT THIS DILUTION) (Note 3)

Deionised or distilled water

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

 







Page last updated October 2015

In this demonstration iron wool is heated with a bunsen flame in the presence of chlorine gas and the vapours of bromine and iodine. An exothermic redox reaction occurs which gives iron(III) halides as coloured solids. The vigour of the reaction depends on the reactivity order of the halogens.

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