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Chem 2 Revision - Metals (Unit 2)
1. Basic ideas
Only less reactive metals such as gold, silver, copper and platinum are found uncombined in
the Earth's crust. We call these metals native metals.
Most metals are found as compounds with oxygen or sulphur in metal ores.
A metals ore…

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Studies have now shown that using certain plants to extract metals from soil is commercially
feasible. These specially selected plants - called hyperaccumulators - are known for their
ability to take up through their roots and store particular metals. However, the plant has no
way of getting rid of the…

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Gold, because it is so unreactive, is found as the native metal and not as a compound. It does
not need to be chemically extracted from its ore, but chemical reactions may be needed to
remove other elements that might contaminate the metal.
7. Advantages and disadvantages of mining metals…

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Similarly, iron can be used to displace copper from copper sulphate solution. (Miners do this
by putting iron filings into a solution of copper minerals from copper mines.) This reaction can
be written as an ionic equation:

F e(s) + Cu2+(aq) F e2+(aq) + Cu(s)

The copper (II) ions have…

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C aO + SiO2 CaSiO3

The main percentage of iron that leaves the blast
furnace in the impure iron is approximately 96%. The
other 4% is made up of impurities of which the main
one is carbon, but also includes silicon, sulphur,
phosphorus and manganese. These impurities get rid
of…

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stressed, they simply stretch, squash or bend, unlike materials with other types of bonding,
such as brick, china or glass.

Pure metals are usually too soft to be very useful for most purposes, so we add other metals
or carbon to form alloys which have useful properties. The atoms of…

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Brass Zn 70% Harder than Copper. Corrosion resistant
Cu 30% screws, musical
instruments.

Bronze Cu 90% Hard, strong, corrosion Statues, bearings.
Sn 10% resistant.

Cupro-nickel Cu 70% Hard, strong, corrosion `Silver' coins.
Ni 30% resistant.

Duralumin Al 94% Low density; higher Aircraft bodies.
Cu 4% strength/mass ration
Mg 1% than…

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Smart alloys are shape memory alloys. If they are bent into another shape and then
reheated, they return to their original shape. They can be used to repair broken bones, or in
orthodontics to push teeth into the correct position. An example of a smart alloy is nitinol.



Smart alloys…

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T iO2 (2 ×O2-) + T i4+

First, it is made into titanium chloride. This is done by mixing it with carbon and heating it in a
furnace at 800oC. Then, chlorine gas is passed into the furnace, making titanium(IV) chloride
TiCl4 (gaseous at this current temperature) and carbon monoxide.…

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It is therefore not attacked by air, water or acids at room temperature.

When molten, it reacts with carbon, oxygen and nitrogen, which makes it brittle.



Titanium has a much higher melting point than that of aluminium.

Metal Melting Point (oC)

Titanium 1660

Aluminium 660

Iron 1535



16. The hardness…

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