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redox rusting and iron - Coggle Diagram
redox rusting and iron
redox
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- many reactions can be simply described as oxidation or reduction in terms of the change in the content of oxygen or hydrogen
- reduction is the reverse of oxidation
redox and displacement
a displacement reaction is one in which a more reactive metal takes the place of a less reactive metal in a compound. this process involves the transfer of electrons
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when a solid metal compounds (often oxides) are heated with a solid metal, a displacement reaction can occur- it is a redox reaction
rusting
is hydrated iron, sometimes written as Fe³O³.xH2O
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preventing rusting
paint is used to protect cars, bridges and railings
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plastic coating, such as those used to cover bicycle handlebars, garden chairs and dish tracks. car manufacturers are increasingly using plastic cars to reduce the problem of rust
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cans for food are made from steel and are coated on both sides with a thin layer of tin. tin is unreactive and non-toxic. it is deposited on the steel by electrolysis
chromium is used to coat steel, giving it a shiny, attractive apperance. this is used for some vehicle bumpers and bicycle handlebars. chromium can be applied by electrolysis
iron can be coated in zinc - the is called galvanising. zinc is more reactive than iron and oxidises readily to form a layer of zinc oxide. galvanising protects by sacrificial protection if the surface is scratched, and also the zinc oxide provides a barrier to air and water
alloying- an alloy is a mixture of two or more elements, at least one of which is a metal, and the resulting mixture has metallic properties. alloys are often stronger and more resistant to corrosion than the pure metals are made from. stainless steel is an alloy that is resistant to corrosion
iron and its extraction
extracting iron
Iron is used in bridges, buildings and other structures because it is strong.
blast furnace
- Iron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as haematite contain iron(III) oxide, Fe2O3. The oxygen must be removed from the iron(III) oxide to leave the iron behind.
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It is so hot in the blast furnace that carbon monoxide is the reducing agent which reduces the iron(III) oxide. The equation for the reduction of iron(III) oxide in the blast furnace is:
iron(III) oxide + carbon monoxide → iron + carbon dioxide
Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)
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raw materials
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Coke: Carbon Burns in air to produce heat, and reacts to form carbon monoxide (needed to reduce the iron oxide)
Limestone: Calcium carbonate Helps to remove acidic impurities from the iron by reacting with them to form molten slag
Air: Oxygen Allows the coke to burn, and so produces heat
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