2.5 - Extraction and uses of metals Flashcards
What are minerals?
Most metals are found in the earths crust are combined with other elements
What are ores?
An ore is a sample of rock that contains enough of a mineral for it to be worthwhile to extract the metal.
What are native?
A few very unreactive metals such as gold and silver exist uncombined elements.
What methods can be used to extract metals and how does the reactivity series determine this?
How a metal is extracted depends on its position in the reactivity series. Manufacture wants to use the cheapest possible method for extracting an ore. Factors are taken into account.
Cost of energy
Cost of reducing agent
How are metals extracted that are lower than carbon in the reactivity series?
For metals below carbon in the reactivity series the cheapest method of reducing the ore is to heat it with carbon.
Extraction of iron one of the main ores of iron contains iron oxide can be extracted heating with carbon.
Carbon is higher in the reactivity series than iron and will take the oxygen away from the iron oxide. Redox reaction reduced from Fe2O3 to Fe in the reaction and C oxidised to CO carbon is the reducing agent.
Extraction carried out in a blast furnace.
What is an alloy?
An alloy is a mixture of a metal with usually other metals or carbon. Brass is a mixture of copper and zinc.
Alloys are harder than the individual pure metals from which they are made because there are different metals and elements have slightly different sized atoms. This breaks up the regular lattice arrangement make it more difficult for layers of irons to slide over each other..
How are metals extracted above carbon in the reactivity?
Ores of metals higher in the reactivity series than zinc can’t be reduced using carbon. This is because metal more reactive than carbon and therefore carbon cannot take oxygen from metal oxide metals extracted by electrolysis.
Aluminium extracted by electrolysis of aluminium oxide dissolved in a molten salt cryolite.
Requires huge amount of electricity which makes it expensive. Much more expensive with iron can also be extracted by electrolysis but because process is so expensive is not used.
Some metals such as titanium extracted by heating the compound with more reactive metal.
What are the uses of aluminium?
Pure aluminium is not very strong, so aluminium alloys are normally used. Aluminium wires.
Uses include planes, electricity cables , pans.
What is mild steel and what are its uses?
Mild steel is the name given to an alloy of iron containing small % of carbon. This increases hardness and strength of the iron. Mild steel is a strong material that can be easily hammered into different shapes and drawn wires. (car bodies)
However mild steel rusts when exposed to o2 and water much more dense than aluminium. Some car bodies made from aluminium car body will not rust.
What is high carbon steel?
High carbon steel is iron containing a small % of carbon. High carbon steel is harder and more resistant to wear than mild steel but more brittle used for cutting tools (Knives)
What is stainless steal?
Stainless steel as an alloy of iron, chromium and nickel. Chromium forms a strong oxide layer in the same way as aluminium and this oxide layer protects iron stainless steel resistant to corrosion.
Knives forks are uses
What are uses of Copper?
Electrical wires - very good conductor of electricity and ductile
Pots and Pans - Very good conductor of heat unreactive
