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Questions and Answers
What is the main ore of aluminium from which it is extracted?
What is the main ore of aluminium from which it is extracted?
Why can't aluminium be extracted by reduction using carbon?
Why can't aluminium be extracted by reduction using carbon?
What does the process of thermal decomposition of calcium carbonate produce?
What does the process of thermal decomposition of calcium carbonate produce?
What component of the electrolytic cell is crucial for the extraction of aluminium?
What component of the electrolytic cell is crucial for the extraction of aluminium?
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Which reaction occurs when calcium oxide reacts with silicon dioxide?
Which reaction occurs when calcium oxide reacts with silicon dioxide?
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What method is used to extract potassium from its compounds?
What method is used to extract potassium from its compounds?
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Which of the following metals is extracted using a blast furnace?
Which of the following metals is extracted using a blast furnace?
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In the electrolysis process, what is required to extract metals such as sodium and potassium?
In the electrolysis process, what is required to extract metals such as sodium and potassium?
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Why are metals higher in the reactivity series less resistant to oxidation?
Why are metals higher in the reactivity series less resistant to oxidation?
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What is the most significant component in the electrolysis of metals extracted from molten compounds?
What is the most significant component in the electrolysis of metals extracted from molten compounds?
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What is the primary reason for dissolving aluminium oxide in molten cryolite during the extraction process?
What is the primary reason for dissolving aluminium oxide in molten cryolite during the extraction process?
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Which reaction occurs at the cathode during the electrolysis of aluminium?
Which reaction occurs at the cathode during the electrolysis of aluminium?
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What is produced at the anode during the electrolysis of aluminium?
What is produced at the anode during the electrolysis of aluminium?
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How does the carbon in the graphite anodes affect the electrolysis process?
How does the carbon in the graphite anodes affect the electrolysis process?
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Why does the anode need to be replaced regularly in the electrolysis process?
Why does the anode need to be replaced regularly in the electrolysis process?
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When aluminium oxide is purified from bauxite, which of the following is formed?
When aluminium oxide is purified from bauxite, which of the following is formed?
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What is the role of the graphite lining in the electrolysis cell?
What is the role of the graphite lining in the electrolysis cell?
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What is a significant expense associated with the extraction of aluminium?
What is a significant expense associated with the extraction of aluminium?
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Study Notes
Extraction and Uses of Metals
- Metals are often chemically combined with other substances forming ores
- Metal ores are rocks containing enough of a metal to make extraction worthwhile
- Metals are extracted from ores using processes like electrolysis, blast furnaces, or reacting with more reactive materials
- Many metal ores are oxides, requiring reduction to remove oxygen
- Common oxide ore examples include iron (hematite) and aluminium (bauxite)
- Unreactive metals, like gold and platinum, are found as pure elements in the Earth's crust
- A metal can reduce another metal if it’s more reactive than the metal bonded to the oxygen
Extracting Metals
- Reactivity series determines extraction method
- Most reactive metals (top of series) are extracted by electrolysis of molten chlorides or oxides
- Less reactive metals are extracted by reduction with carbon (e.g., iron)
Extraction of Iron from Hematite
- Iron is extracted from its ore, hematite, in a blast furnace
- Modern blast furnaces produce around 10,000 tonnes of iron per day
- The extraction is a continuous process with fresh raw materials added and products removed
- Raw materials used in the blast furnace include iron ore (hematite), coke, and limestone
- Three zones in the blast furnace contribute to extraction:
- Zone 1: Coke burns to form carbon dioxide (C + O₂ → CO₂)
- Zone 2: Carbon dioxide is reduced to carbon monoxide (CO₂ + C → 2CO)
- Zone 3: Carbon monoxide reduces iron oxide to iron (Fe₂O₃ + 3CO → 2Fe + 3CO₂)
- Limestone (CaCO₃) is added to remove impurities as molten slag
Removal of Impurities
- Limestone (CaCO₃), when heated, produces calcium oxide (CaO).
- Calcium oxide reacts with silicon dioxide (SiO₂) in the ore to form calcium silicate (CaSiO₃) which is a slag that floats on the molten iron
Extraction of Aluminium
- Aluminium is a highly reactive metal (above carbon in the reactivity series)
- Its main ore is bauxite, containing aluminium oxide (Al₂O₃)
- Due to its high reactivity, aluminium is extracted by electrolysis
- Bauxite is purified to form aluminium oxide (Al₂O₃), which is dissolved in molten cryolite
- Electrolysis is carried out in a steel container lined with graphite
- Oxygen is produced at the anode (positive electrode) and aluminium at the cathode (negative electrode), requiring a considerable amount of electrical energy
Uses of Metals
- Different metals have various properties affecting their uses
- Uses of particular metals are detailed (properties and their uses) for aluminium, copper, and iron and steel alloys
Alloys
- Alloys are mixtures of two or more metals, or a metal and a non-metal (e.g., carbon)
- Alloys often have different properties from their constituent metals
- Alloys are generally stronger, harder, more resistant to corrosion, or have better high-temperature properties than pure metals
- Their distorted atomic arrangement makes them more resistant to deformation because atoms don’t slide past each other as easily.
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Description
This quiz covers the methods of metal extraction, including techniques employed for various ores such as hematite and bauxite. It also explores the reactivity series and the chemical processes used to separate metals from their ores. Test your knowledge on this essential topic in metallurgy!
