In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because
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Correct Answer: Option B
Explanation:
The correct answer is: B. it makes bauxite melt at a lower temperature ✅
Here's why:
In the electrolytic extraction of aluminium from purified bauxite (Alâ‚‚O₃), the melting point of pure alumina is very high — around 2000°C. Operating at this temperature would be extremely costly and energy-intensive.
To solve this, cryolite (Na₃AlF₆) is added as a flux. It lowers the melting point of the mixture to about 950°C, making the process more economical and practical.
Quick breakdown of the options:
- A. it makes bauxite a better conductor of electricity – Not directly. Cryolite improves the overall conductivity of the molten mixture, but its primary purpose is to lower melting point.
- B. it makes bauxite melt at a lower temperature – ✅ Correct. This is the main reason cryolite is used.
- C. it makes aluminium purer – No, the purity is controlled by the process, not cryolite.
- D. it prevents aluminium from getting oxidized – No, aluminium is formed at the cathode where oxidation doesn’t occur.
- E. it protects the carbon electrodes – Not its main function.
The correct answer is: B. it makes bauxite melt at a lower temperature ✅
Here's why:
In the electrolytic extraction of aluminium from purified bauxite (Alâ‚‚O₃), the melting point of pure alumina is very high — around 2000°C. Operating at this temperature would be extremely costly and energy-intensive.
To solve this, cryolite (Na₃AlF₆) is added as a flux. It lowers the melting point of the mixture to about 950°C, making the process more economical and practical.
Quick breakdown of the options:
- A. it makes bauxite a better conductor of electricity – Not directly. Cryolite improves the overall conductivity of the molten mixture, but its primary purpose is to lower melting point.
- B. it makes bauxite melt at a lower temperature – ✅ Correct. This is the main reason cryolite is used.
- C. it makes aluminium purer – No, the purity is controlled by the process, not cryolite.
- D. it prevents aluminium from getting oxidized – No, aluminium is formed at the cathode where oxidation doesn’t occur.
- E. it protects the carbon electrodes – Not its main function.