Extraction Of Metals
Overview
Most metals are not found pure in the ground; they are locked up in ores as compounds, usually oxides. Winning the metal back is a question of energy and reactivity: a reactive metal clings to its ore and needs electricity to free it, while a less reactive metal can be prised out with carbon. The reactivity series is the master key.
In this lesson you will learn how a metal's position in the reactivity series decides how it is extracted, follow the extraction of iron from hematite in the blast furnace step by step, and see why aluminium, high in the series, must be extracted by electrolysis from bauxite using cryolite and carbon anodes.
Objectives
- Describe the ease in obtaining metals from their ores, related to the position of the metal in the reactivity series.
- Describe the extraction of iron from hematite in the blast furnace, limited to: (a) the burning of carbon (coke) to provide heat and produce carbon dioxide (b) the reduction of carbon dioxide to carbon monoxide (c) the reduction of iron(III) oxide by carbon monoxide (d) the thermal decomposition of calcium carbonate / limestone to produce calcium oxide (e) the formation of slag Symbol equations are not required.
- State that the main ore of aluminium is bauxite and that aluminium is extracted by electrolysis.
- [Supplement] State the symbol equations for the extraction of iron from hematite (a) C + O₂ → CO₂ (b) C + CO₂ → 2CO (c) Fe₂O₃ + 3CO → 2Fe + 3CO₂ (d) CaCO₃ → CaO + CO₂ (e) CaO + SiO₂ → CaSiO₃.
- [Supplement] Describe the extraction of aluminium from purified bauxite / aluminium oxide, including: (a) the role of cryolite (b) why the carbon anodes need to be regularly replaced (c) the reactions at the electrodes, including ionic half-equations Details of the purification of bauxite are not required.
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Extraction Of Metals. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- How is a metal more reactive than carbon usually extracted? A. reduction with carbon B. electrolysis C. found native D. heating in air Answer: B
- What is the main ore of iron? A. bauxite B. hematite C. cryolite D. limestone Answer: B
- In the blast furnace, the reducing agent for iron(III) oxide is: A. oxygen B. limestone C. carbon monoxide D. slag Answer: C
- Why is cryolite used in the extraction of aluminium? A. it is the ore B. it lowers the melting point of aluminium oxide C. it forms slag D. it reduces the aluminium Answer: B
- Why do the carbon anodes in aluminium extraction need replacing? A. they dissolve in cryolite B. oxygen reacts with them to form carbon dioxide C. aluminium coats them D. they melt Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
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