Extraction of iron on a match head

In this experiment, students reduce iron(III) oxide with carbon on a match head to produce iron. The experiment provides a quick example of metal extraction, and can be used to highlight aspects of the reactivity series.

This practical can easily be carried out on an individual basis by students. The experiment itself is very quick to do provided that the apparatus and chemicals are already set out around the laboratory.

Equipment

Apparatus

• Eye protection
• Match (non-safety) (see note 5 below)
• Tongs (crucible tongs)
• Weighing boat (small white plastic ones are ideal)
• Spatula
• Bunsen burner
• Heat resistant mat
• Magnet (eg bar magnet)

Chemicals

Small amounts of the following (see note 6 below):

• Iron(III) oxide powder
• Sodium carbonate powder (IRRITANT)
• Water

Health, safety and technical notes

• Read our standard health and safety guidance.
• Wear eye protection throughout.
• Iron(III) oxide powder, Fe₂O₃(s) – see CLEAPSS Hazcard HC055A.
• Sodium carbonate powder, Na₂CO₃(s), (IRRITANT) – see CLEAPSS Hazcard HC095A.
• The experiment works best with non-safety matches. These are often referred to as ‘strike anywhere’ matches and have a pinkish-red head.
• Small amounts (a few spatula measures are sufficient) of each of the powders can be provided in, for example, Petri dishes or watch glasses. Groups of students can share the chemicals. The water can be provided in a small beaker.

Procedure

1. Dip the head of a match in water to moisten it.
2. Roll the damp match head first in sodium carbonate powder, then in iron(III) oxide powder.
3. Hold the match in a pair of tongs. Put the head of the match into a blue Bunsen flame (air-hole open). The match will flare and burn. Do not allow the match to burn more than half way along its length.
4. Allow the match to cool for about 30 seconds.
5. Use a spatula to crush the charred part of the match into a small plastic weighing boat.
6. Move a magnet around under the weighing boat – some of the small particles will move around in the weighing boat following the track of the magnet. Do not dip the magnet into the particles directly, unless you have first wrapped the magnet in cling film – any pieces of iron will stick to the magnet and will be difficult to clean off.

Teaching notes

A simple equation for the reaction would be:

Iron(III) oxide + carbon → iron + carbon dioxide

2Fe₂O₃(s) + 3C(s) → 4Fe(s) + 3CO₂(g)

Carbon is more reactive than iron. The iron oxide is reduced by the carbon (the oxygen is removed) to form metallic iron.

The sodium carbonate fuses easily and brings the iron oxide into close contact with the carbon.