Extraction & The Reactivity Series

  • The Earth’s crust contains metals and metal compounds such as gold, copper, iron oxide and aluminium oxide.
  • Useful metals are often chemically combined with other substances forming ores.
  • A metal ore is a rock that contains enough of the metal to make it worthwhile extracting.
  • They have to be extracted from their ores through processes such as electrolysis, using a blast furnace or by reacting with more reactive material.
  • In many cases the ore is an oxide of the metal, therefore the extraction of these metals is a reduction process since oxygen is being removed.
  • Common examples of oxide ores are iron and aluminium ores which are called haematite and bauxite respectively.
  • Unreactive metals do not have to be extracted chemically as they are often found as the uncombined element.
  • This occurs as they do not easily react with other substances due to their chemical stability.
  • Examples include gold and platinum which can both be mined directly from the Earth’s crust.

Extraction & REDOX

  • The most reactive metals are at the top of the series.
  • They readily lose electrons to form cations and are hence oxidised easily.
  • The opposite occurs for metals placed lower down as they are unreactive and do not easily lose their electrons.
  • The tendency to become oxidised is thus linked to how reactive a metal is and therefore its position on the reactivity series.
  • Metals higher up are therefore less resistant to oxidation than the metals placed lower down which are more resistant to oxidation.
  • The position of the metal on the reactivity series determines the method of extraction.
  • Higher placed metals (above carbon) have to be extracted using electrolysis as they are too reactive and cannot be reduced by carbon.
  • Lower placed metals can be extracted by heating with carbon which reduces them.

Extraction & REDOX Table, IGCSE & GCSE Chemistry revision notes

Extraction of Iron

  • The main ore of iron is haematite.
  • Iron is extracted from the haematite in a blast furnace through reduction with carbon. 
  • The process is very important industrially due to the large scale use of iron in industry and society.

Carbon Extraction of Iron

Extraction of Iron from its ore using Carbon, IGCSE & GCSE Chemistry revision notes

Diagram of the extraction of iron in a blast furnace

Raw Materials
Iron ore (Haematite), coke, limestone and air. Iron ore, coke and limestone are mixed together and fed into the top of the blast furnace. Hot air is blasted into the bottom of the blast furnace.

Zone 1
Coke is used as the starting material. It is an impure carbon and burns in the hot air blast to form carbon dioxide. This is a strongly exothermic reaction:

C(s) + O2(g) → CO2(g)

Zone 2
At the high temperatures in the furnace, carbon dioxide reacts with coke to form carbon monoxide:

CO2(g) + C (s) → 2CO (g)

Zone 3
Carbon monoxide (the reducing agent) reduces the Iron (III) oxide in the iron ore to form iron, which will melt and collect at the bottom of the furnace, where it is tapped off:

Fe2O3 (s) + 3CO (g) → 2Fe (IIl) + 3CO2 (g)

Limestone is added to the furnace to remove impurities in the ore. The calcium carbonate in the limestone decomposes to form calcium oxide:

CaCO3 (s) → CaO (s) + CO2 (g)

The calcium oxide reacts with the silicon dioxide, which is an impurity in the iron ore, to form calcium silicate. This melts and collects as a molten slag floating on top of the molten Iron which is tapped off separately:

CaO (s) → SiO2 (s) + CaSiO3 (l)

AQA GCSE Chemistry Notes

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Morgan Curtin Chemistry

Author: Morgan

Morgan’s passion for the Periodic Table begun on his 10th birthday when he received his first Chemistry set. After studying the subject at university he went on to become a fully fledged Chemistry teacher, and now works in an international school in Madrid! In his spare time he helps create our fantastic resources to help you ace your exams.