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Why are different metals extracted in different ways, and how is iron made in the blast furnace?

Metal ores, extraction by reduction with carbon for metals below carbon in the reactivity series, and the reactions of the blast furnace.

A focused answer to WJEC GCSE Chemistry topic 2.3 on extracting metals, covering ores, why the extraction method depends on reactivity, reduction with carbon, and the reactions that take place inside the blast furnace to make iron.

Generated by Claude Opus 4.89 min answer

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  1. What this topic is asking
  2. Metals, ores and reduction
  3. Reactivity decides the method
  4. The blast furnace
  5. Why the method matters
  6. Try this

What this topic is asking

WJEC wants you to explain why a metal's reactivity decides how it is extracted, and to describe how iron is made by reduction with carbon in the blast furnace. This is part of topic 2.3 Metals and their extraction in Unit 2 of WJEC GCSE Chemistry (3430).

Metals, ores and reduction

Reactivity decides the method

The blast furnace

The furnace runs continuously because heating and cooling such a large structure would waste energy. The limestone (calcium carbonate) first decomposes in the heat to calcium oxide and carbon dioxide; the calcium oxide then reacts with the silica impurity to form molten calcium silicate, the slag, which is tapped off and used to make road material and cement. The iron tapped from the bottom is called cast iron and contains a few per cent of carbon, which makes it hard but brittle, so most of it is later converted to steel by burning off some of the carbon.

Why the method matters

Try this

Q1. State why gold is found in the Earth as the uncombined metal. [1 mark]

  • Cue. Gold is very unreactive, so it does not react to form compounds.

Q2. Name the substance that reduces iron oxide in the blast furnace. [1 mark]

  • Cue. Carbon monoxide.

Exam-style practice questions

Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

WJEC 20183 marksExplain why iron can be extracted from its ore using carbon, but aluminium cannot.
Show worked answer →

A topic 2.3 Explain question on the link between reactivity and method. Iron is less reactive than carbon, so carbon can reduce iron oxide by taking the oxygen away (1 mark). Aluminium is more reactive than carbon, so carbon cannot remove the oxygen from aluminium oxide (1 mark); aluminium must instead be extracted by electrolysis (1 mark). Markers reward comparing each metal with carbon and naming electrolysis for aluminium. A common error is to say carbon is simply cheaper without the reactivity reason.

WJEC 20214 marksDescribe how iron is extracted in the blast furnace, including the reactions that take place.
Show worked answer →

A topic 2.3 structured question. Iron ore (haematite), coke (carbon) and limestone are added to the top of the furnace and hot air is blasted in (1 mark). Carbon burns to form carbon dioxide, which reacts with more carbon to form carbon monoxide (1 mark). Carbon monoxide reduces the iron oxide: iron(III) oxide+carbon monoxide→iron+carbon dioxide\text{iron(III) oxide} + \text{carbon monoxide} \rightarrow \text{iron} + \text{carbon dioxide} (1 mark). Molten iron runs to the bottom, and limestone removes sandy impurities as slag (1 mark). Markers reward the reducing agent, the reduction reaction and the role of limestone.

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