Extracting iron and copper
Ores
A substance is unreactive or inert if it does not easily take part in chemical reactions.Shiny element that is a good conductor of electricity and heat, and which forms basic oxides. such as gold are found in the Earth's The outer layer of the Earth on top of the mantle. as the uncombined A substance made of one type of atom only.. However, most metals are found combined with other elements to form A substance formed by the chemical union of two or more elements..
An A rock containing enough quantities of a mineral for extraction to be possible. is a rock that contains enough of a metal or a metal compound to make extracting the metal worthwhile:
- low-grade ores contain a small percentage of the metal or its compound
- high-grade ores contain a larger percentage
Most metals are extracted from ores found in the Earth's crust. It is more expensive and wasteful to extract a metal from a low-grade ore, but most high-grade ores have already been used.
Extraction methods
The The process of obtaining a metal from a mineral, usually by reduction or electrolysis. method used depends upon the metal's position in the A list of elements in order of their reactivity, usually from most reactive to least reactive.. In principle, any metal could be extracted from its compounds using The decomposition (breakdown) of a compound using an electric current.. However, large amounts of Energy transferred by electricity. are needed to do this, so electrolysis is expensive.
If a metal is less The tendency of a substance to undergo a chemical reaction. than carbon, it can be extracted from its compounds by heating with carbon.
Metal oxide + carbon → metal + carbon dioxide
For example, A term used to describe a liquid substance (eg rock, glass or metal) formed by heating a solid. copper can be produced from copper oxide by heating with carbon:
Copper oxide + carbon → copper + carbon dioxide
2CuO(s) + C(s) → 2Cu(l) + CO2(g)
Copper oxide is The loss of oxygen, gain of electrons, or gain of hydrogen by a substance during a chemical reaction. as carbon is The gain of oxygen, or loss of electrons, by a substance during a chemical reaction., so this is an example of a When reduction and oxidation take place at the same time. reaction.
Remember:
- oxidation is the gain of oxygen by a substance
- reduction is the loss of oxygen by a substance
- a redox reaction involves the loss and gain of oxygen
Note: the impure copper is purified by electrolysis.
The table summarises the extraction methods used for different metals.
Extracting iron
As iron is below carbon in the reactivity series it can be Take the place of another substance in a chemical reaction. For example, a metal can displace a less reactive metal from its oxide, removing oxide ions from the less reactive metal and becoming an oxide itself. from its compounds by heating with carbon. Iron is extracted from iron ore in a large container called a blast furnace. Iron(III) oxide is reduced to molten iron when it reacts with carbon. The overall reaction is:
Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)
The iron oxide is reduced and the carbon is oxidised.
These reactions happen because carbon is more reactive than iron, so it can displace iron from iron compounds. Extracting a metal by heating with carbon is cheaper than using electrolysis.
Question
Write a A chemical equation written using the symbols and formulae of the reactants and products, so that the number of units of each element present is the same on both sides of the arrow. for the reaction between tin(IV) oxide and carbon, forming molten tin and carbon dioxide.
SnO2(s) + C(s) → Sn(l) + CO2(g)
