In the extraction of Al by electrolysis, why is it necessary to dissolve AI2O3 in molten cryolite?
Correct answer: B. To decrease high melting point of the electrolyte
- A. Cryolite provides the ions needed to carry current
- B. To decrease high melting point of the electrolyte
- C. Cryolite reacts with AI2O3 to form ions
- D. Molten AI2O3 would not conduct electricity
Explanation
The correct answer is B) To decrease high melting point of the electrolyte. Dissolving aluminum oxide in cryolite significantly reduces the melting point of the electrolyte from about 2072°C to around 950°C, making the extraction process economically viable and technically feasible. Option A is incorrect because cryolite does not provide ions; it is a solvent. Option C is incorrect because there is no chemical reaction forming ions between cryolite and aluminum oxide. Option D is incorrect because it implies that molten aluminum oxide cannot conduct electricity, whereas the real issue is its impractically high melting point.
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