Discovery Science 2010 Term 3 ABDEF Task Alex Coffey Aim: To investigate the increase/decrease in rust and corrosion when dipped in different solutions. Corrosion is the reaction between a metal and it’s surrounding environments. Corrosion occurs when a metal (for example Copper) and different environments (such as water, air, acids, bases, etc. ) come into contact. Corrosion is the act of deterioration in metals. [1] A chemical reaction occurs between the metal and it’s environments Eg. Copper + Oxygen ( Copper Oxide Cu (I) + O ( CuO Rust is very similar to corrosion but only occurs in iron and steel (an iron alloy).
Rust is formally known as oxidation, which occurs when Oxygen (O) comes into contact with iron (Fe). Overtime, the oxygen reacts and combines chemically with the iron, forming a substance named Iron Oxide (Fe2O3), which weakens the physical bond of the iron. [2] Chemical Equation of Rust: 4Fe + 3O2 –> Fe2O3[3] To maximize rust, a certain level of moisture is needed in the air (humidity level). To minimize rust, there needs to either be a block to reduce contact between iron and oxygen, or to coat the iron with an element that reacts to oxygen and makes a rust proof film (zinc).
When iron is coated in zinc it’s commonly known as galvanization. Galvanizing iron is one of the most commonly used techniques of preventing rust. The Zinc around the iron reacts faster and more with the oxygen in the environment then the iron does, thus creating a small film around the iron, blocking from contact with oxygen. The 4 metals that are being used in our experiment are common Steel, Zinc coated Iron (galvanized), Copper, and Aluminium. Steel is commonly used in ships and submarines. Steel is an alloy of mostly iron alloyed with between 0. 2% and 2. % carbon, but the most common steel found on ships is a low carbon alloy. Metals like Magnesium and Chromium can also be added to this alloy for improvements in strength and weight. [4]. Both Copper and Aluminium are alloyed with different materials to create many different alloys that are commonly used on marine transport. Alloys are combinations of chemical compounds, rather then a chemical compound itself. To create an alloy two or more metals are melted together, this is not a chemical change, but it is a physical change. Eg. Brass is an alloy of copper and zinc (mostly copper).
There are no chemical bonds between the two metals but they work together to create a stronger, lighter metal. ———————– [1] Pierre R. Roberge, Corrosion theory, http://www. corrosion-doctors. org/Principles/Theory. htm, Visited 16/8/10 [2] M. Schell & M. Hogan, Shipwrecks and Salvage, p. 10, 12, 23, 25, 35. Visited 12/8/10 [3] P. Wensingten, Chemical Formula of Rust, http://www. chemicalformula. org/rust Visited 17/8/10 [4] J. Stephenson, Teachers’ Domain: Elements of Steel, http://www. teachersdomain. org/resource/phy03. sci. phys. matter. elements/, Visited 16/8/10
