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Extracting iron and copper

Ores

such as gold are found in the Earth's as the uncombined . However, most metals are found combined with other elements to form .

Most metals are extracted from 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.

Learn more on redox in terms of electrons in this podcast.

Extraction methods

The method used depends upon the metal's position in the . In principle, any metal could be extracted from its compounds using . However, large amounts of are needed to do this, so electrolysis is expensive.

If a metal is less than carbon, it can be extracted from its compounds by heating with carbon. Copper is an example of this. Copper mostly occurs as sulfide ores, which are heated in air to convert them to copper(II) oxide. 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)

Copper oxide is as carbon is , so this is an example of a reaction.

The table summarises the extraction methods used for different metals.

List of metals and their extraction methods and reactivity, listen from most to least reactive.

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) + 3C(s) 鈫 2Fe(l) + 3CO(g)

This method of extraction works because carbon is more reactive than iron, so it can iron from iron compounds. Extracting a metal by heating with carbon is cheaper than using electrolysis.

Question

In the reaction of iron(III) oxide with carbon, state which substance is reduced and which substance is oxidised.