Extraction of iron on a match head! 41 Introduction Students reduce iron(III) oxide with carbon on a match head to produce iron in this small scale example of metal extraction. The experiment can be used to highlight aspects of the reactivity series. Lesson organisation This experiment 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. Apparatus and chemicals Eye protection Each student (or pair of students) will need: • Match (non-safety) (see note 1) Tongs (crucible tongs) Weighing boat (small white plastic ones are ideal) Spatula Students will also need access to: Bunsen burner Heat resistant mat Magnet (e.g. bar magnet) Iron(III) oxide powder (Low hazard) (see note 2) Sodium carbonate powder (Irritant) (see note 2) Water (see note 2) Technical notes Iron(III) oxide powder (Low hazard). Refer to CLEAPSS® Hazcard 55A. Sodium carbonate (Irritant). Refer to CLEAPSS® Hazcard 95A. 1 The experiment works best with non-safety matches. These are often referred to as 'strike anywhere' matches and have a pinkish-red head. 2 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. 121 Procedure HEALTH & SAFETY: Wear eye protection • a Dip the head of a match in water to moisten it. b Roll the damp match head first in sodium carbonate powder, then in iron(III) oxide powder. c 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. d Allow the match to cool for about 30 seconds. e Use a spatula to crush the charred part of the match into a small plastic weighing boat. f 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. Reference This experiment has been reproduced from Practical Chemistry: http://www.practicalchemistry.org/experiments/intermediate/elements-compounds-and- mixtures/extraction-of-iron-on-a-match-head,99,EX.html Useful resource Teachers.tv. KS3/4 Science - Banging Chemistry: Fast and Furious http://www.teachers.tv/video/20295 (Website accessed December 2009) Health & Safety checked, June 2007 122 Updated 21 Feb 2008.