Aluminium extraction: a molten mixture and a consumed carbon anode
도입됨| English | 의미 |
|---|---|
| cryolite/ˈkraɪəlaɪt/ | 크리올라이트 |
| anode/ˈænəʊd/ | 양극 |
What would explain this observation?
- Aluminium oxide has a very high melting point. Industrial electrolysis uses a molten oxide–cryolite 冰晶石 mixture instead of simply melting pure oxide at its own high melting temperature.
Build the model
- Electrolysis extracts metals from molten compounds when they are too reactive for carbon reduction or react with carbon.
- It requires energy both to maintain the molten electrolyte and to provide electrical current.
- Aluminium manufacture uses aluminium oxide dissolved in molten cryolite.
- The mixture melts at a lower temperature than pure aluminium oxide, reducing the heating demand.
- cryolite: The material used in the molten mixture to lower the operating temperature of aluminium-oxide electrolysis.
- anode 阳极: The positive electrode in the powered electrolysis model, where oxidation occurs.
Why must carbon anodes be replaced?
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Oxygen forms at the carbon anodes and reacts with them to make carbon dioxide, burning the anodes away - so they are consumed and must be replaced. The aluminium comes from the alumina feed, not the anodes.
Match each technical term to its precise meaning.
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Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Aluminium forms at the negative cathode.
- Oxygen associated with oxide discharge at the positive carbon anode reacts with carbon, forming carbon dioxide in the GCSE account.
- The carbon anode is consumed and needs continual replacement.
- It is therefore not an inert electrode like the one assumed in a simple product-prediction exercise.
In the lab: Interpret a labelled industrial cell using supply polarity, electrolyte composition, metal collection and anode material. Use supplied electricity, temperature or electrode-replacement data to evaluate cost or resource demand. This is an industrial reference case, not a school task to build a hot extraction cell. Avoid adding unrequired plant details that obscure the two required explanations.
Which two habits make the investigation or model in this case more defensible?
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Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: a supplied operating comparison states heating-energy demand of 900 units for the pure-oxide scenario and 600 for the mixture scenario on the same basis.
- Reduction=300 units, percentage reduction=300/900×100=33.3%.
- This fictional dataset illustrates a stated comparison; it is not a published industrial efficiency claim or total-life-cycle energy estimate.
Your turn: Supplied heating demands are 800 units and 600 units on the same basis. Find percentage reduction.
Supplied heating demands are 800 units and 600 units on the same basis. Find percentage reduction.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
The result is 25 %. Known: demand falls from 800 to 600 units on the same basis. Reduction = 200 units. Percentage reduction = 200/800 x 100 = 25%. This compares heating demand only, not the whole energy bill.
Check the conclusion and its limits
- Cryolite does not provide the aluminium metal being extracted from the alumina feed in the simplified account.
- Lower heating demand does not remove the electrical-current requirement.
- Carbon consumption follows its chemical reaction at the anode, not simply mechanical wear.
- Do not predict oxygen collection unchanged at an anode that reacts with it.
Not true: Using cryolite removes the need for electrical current during aluminium extraction. Cryolite lowers the operating temperature by dissolving the alumina - it saves heating energy. The electrolysis itself still runs on electrical current, which drives the whole separation.
- Electrolysis extracts metals from molten compounds when they are too reactive for carbon reduction or react with carbon.
- Aluminium forms at the negative cathode.
- Watch for: cryolite does not provide the aluminium metal being extracted from the alumina feed in the simplified account.
Using cryolite removes the need for electrical current during aluminium extraction.
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Cryolite lowers the operating temperature by dissolving the alumina - it saves heating energy. The electrolysis itself still runs on electrical current, which drives the whole separation.
The material used in the molten mixture to lower the operating temperature of aluminium-oxide electrolysis: write the technical term.
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cryolite means The material used in the molten mixture to lower the operating temperature of aluminium-oxide electrolysis.