The Chemistry in D&T


Chemical elementsI used to be a chemistry teacher so I was very pleased to read the article Chemical Elements in the latest issue of D&T Practice. Using the aesthetics of chemistry to inspire design is a novel approach to stimulating creativity. I do remember teaching the ‘controlled explosion’ mentioned in the article – the thermite reaction if I’m not mistaken, in which aluminium, being more reactive than iron grabs the oxygen from iron oxide in a spectacular redox reaction forming aluminium oxide and leaves behind a very hot blob of molten iron. The reaction is used to join railway tracks. This reaction should intrigue D&T teachers. If aluminium is MORE reactive than iron how come we use aluminium for saucepans. Shouldn’t they corrode more rapidly than iron which generally rusts very quickly in moist air. The answer of course is that iron oxide does not adhere strongly to the underlying iron, falling off and revealing more iron to undergo reaction with the moist air. Aluminium on the other hand oxidises in air to form an oxide layer that is strongly bonded to the underlying aluminium thus protecting this aluminium from further reaction. This foray into the reactivity series led me to wonder about the role of chemistry in D&T beyond that of inspirational aesthetics. School chemistry courses in England deal with electrolysis at Key Stage 4 and pupils will be taught about the deposition of copper atoms from a solution contain copper ions by means of an electric current. This deposition by electrolysis provides the possibility of laying down copper onto brass. Simple brass body adornments can be embellished with intricate copper patterns in this way. And then I remembered a wonderful book from the Crafts Council – The Colouring, Bronzing and Patination of Metals – a splendid collection of recipes for altering the colour of copper and brass. Embedding a piece of brass in sawdust moistened with ammonium carbonate solution gives rise to a strongly adhering green patina as speckles where the sawdust has made contact with the metal. Even more impressive is the reaction of red-hot copper with steam and boiling water which gives the copper a wonderfully rich deep red colour. So if you are thinking of teaching a body adornment project you might consider asking your pupils to explore some chemical reactions as a precursor.

A colleague asked, “Why would a D&T teacher bother with all this, after all it’s not on the syllabus?” Two answers spring to mind. First and foremost, the pupils might find it interesting and secondly, links with science are an important facet of D&T and a key feature of the new D&T GCSE.

And whilst I’m in the chemistry – D&T zone I note that it’s through the application of the reactivity series that we can get metals from rocks. A standard Key Stage 3 chemistry practical is roasting malachite to turn it into copper oxide and then roasting the copper oxide with charcoal to get metallic copper. To get enough copper to make a small body adornment such as a ring or a brooch the reaction would need to be scaled up so special care would be needed. Something one might do in an afterschool STEM club with a group of interested pupils. Starting with a small bag of green rock and ending up with a copper bracelet would surely be a great chemistry D&T experience. And if you do try using chemistry in your D&T lessons then do please let David and Torben know all about it.

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