Iron and Aluminium Miss Jan
Iron and aluminium SLOs • investigate the reactions of iron and aluminium with oxygen, water, and acids • be able to explain the different reactivity of these two metals
Rusting experiment Number 1-7 down the page – record observations
Results • Things needed for rusting are: • Conditions that speed up rusting are: • Conditions that slow down rusting are: Oxygen and water (and of course, iron) Salt, exposure to oxygen Sacrificial metal, dry air
“Iron and Aluminium” sheet • Answer the true or false questions 1A The chemical symbol for iron is Ir. 1B Iron is produced when iron oxide reacts with carbon. 1C The other product formed when iron oxide is reduced is carbon dioxide. 1D Salt is necessary for rusting to occur. 1E Rust is iron sulfide. F Fe T T F F oxide
T 2A Aluminium is produced at Tiwai Point in Southland. 2B Aluminium is used in power wires because it is a good conductor of heat. 2C Aluminium can be made by reducing aluminium oxide with carbon. 2D Aluminium is a very unreactive metal. F electricity F Chemical reduction F
Iron rust is porous – allows oxygen to enter the metal, which allow more rusting
Rusting Aluminium? • Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion. Aluminum oxide corrosion also looks a lot more like aluminum, so it isn't as easy to notice as rusted iron.
“How to prevent rusting” sheet • Each table group read through and summarize one method of preventing rust. Then report to back to the class – report should contain: • What is this method? • How does it work?
Sacrificial metal To be bolted onto the hull of the boat Why is it labeled “do not paint”?
Galvanised iron Coat of zinc – prevent water or oxygen from reacting with iron
Electroplating Chrome and nickel coating
Questions about rusting • Iron oxide • Iron, water, oxygen • Iron + oxygen iron oxide • Brass (Cu + Zn) does not rust. Steel (99% Fe) rusts • Painting provides a barrier to water and oxygen, preventing them from reacting with iron
Two sacrificial metals: magnesium and zinc • Hull of ship or drilling platform, hot water heater • Zinc • Zinc prevents water or oxygen from reaching iron. Also acts as sacrificial metal (will corrode before iron)