Extracting iron and copper
Reactions of metals with oxygen
Many metalShiny element that is a good conductor of electricity and heat, and which forms basic oxides. react with oxygen to make metal oxides. For example, magnesium burns rapidly in air:
Magnesium + oxygen 鈫 magnesium oxide
2Mg(s) + O2(g) 鈫 2MgO(s)
The reactions are oxidationThe gain of oxygen, or loss of electrons, by a substance during a chemical reaction. reactions because the metal gains oxygen.
Oxygen can be removed from metal oxides in chemical reactions. For example:
Zinc oxide + carbon 鈫 zinc + carbon dioxide
2ZnO(s) + C 鈫 2Zn(s) + CO2(g)
In this reaction, carbon is oxidised because it gains oxygen. At the same time, copper oxide is reductionThe loss of oxygen, gain of electrons, or gain of hydrogen by a substance during a chemical reaction. because oxygen is removed from it.
Ores
unreactiveA substance is unreactive or inert if it does not easily take part in chemical reactions. metals such as gold are found in the Earth's crustThe outer layer of the Earth on top of the mantle. as the uncombined elementA substance made of one type of atom only.. However, most metals are found combined with other elements to form compoundA substance formed by the chemical union of two or more elements.. Chemical reactions are needed to extractionThe process of obtaining a metal from a mineral, usually by reduction or electrolysis. metals from their compounds.
Most metals are extracted from oreA rock containing enough quantities of a mineral for extraction to be possible. found in the Earth's crust. An ore is a rock that contains enough of a metal or a metal compound to make extracting the metal worthwhile.
Extracting copper
The extraction method used depends upon the metal's position in the reactivity seriesA list of elements in order of their reactivity, usually from most reactive to least reactive..
If a metal is less reactiveThe tendency of a substance to undergo a chemical reaction. than carbon, it can be extracted from its compounds by heating with carbon. Copper is an example of this. moltenA 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 鈫 copper + carbon dioxide
2CuO(s) + C(s) 鈫 2Cu(l) + CO2(g)
Metal oxide + carbon 鈫 metal + carbon dioxide
For example,
Copper oxide is reduced as carbon is oxidised, so this is an example of a redox reactionWhen reduction and oxidation take place at the same time..
The table summarises the extraction methods used for different metals.
Although an unreactive metal is found as the metal itself, chemical reactions are often needed to remove other elements that might contaminate it.
Extracting iron
Iron(III) oxide is reduced to molten iron when it reacts with carbon. One of the products is carbon monoxide:
iron(III) oxide + carbon 鈫 iron + carbon monoxide
Fe2O3(s) + 3CO(g) 鈫 2Fe(l) + 3CO2(g)
This method of extraction works because carbon is more reactive than iron, so it can displaceTake 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. iron from iron compounds. Extracting a metal by heating with carbon is cheaper than using electrolysisThe decomposition (breakdown) of a compound using an electric current..
Question
In the reaction of iron(III) oxide with carbon, state which substance is reduced and which substance is oxidised.
Carbon gains oxygen, so it is oxidised. Iron(III) oxide loses oxygen, so it is reduced.