In the electrolytic extraction of aluminum, the function of the molten cryolite is to
precipitate aluminium hdroxide
lower the melting point of aluminium oxide
act as a raw materials
act as a solvent
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In the electrolytic extraction of aluminum, the function of the molten cryolite (Na3AlF6) is to act as a solvent and lower the melting point of aluminum oxide (Al2O3).
Specifically, the roles of molten cryolite in the electrolytic extraction of aluminum are:
1. Solvent: Cryolite dissolves aluminum oxide (Al2O3) at high temperatures, forming a molten electrolyte solution. This allows the aluminum oxide to dissociate and undergo electrolysis.
2. Lower melting point: Pure aluminum oxide has an extremely high melting point of around 2,050°C, which makes it impractical for electrolysis. However, when mixed with cryolite, the melting point of the mixture is significantly reduced to around 950°C, making the electrolysis process more feasible.
3. Increase conductivity: The molten cryolite-aluminum oxide mixture is an excellent conductor of electricity, which is essential for the electrolytic process to occur efficiently.
4. Protect carbon anodes: The cryolite also helps to protect the carbon anodes used in the electrolytic cell from oxidation by forming a protective layer around them.
In summary, the presence of molten cryolite in the electrolytic extraction of aluminum serves as a solvent for aluminum oxide, lowers the melting point of the electrolyte mixture, increases electrical conductivity, and protects the carbon anodes from oxidation, thereby facilitating the efficient electrolytic production of aluminum.
The correct option is:
B.
Lower the melting point of aluminum oxide
As I explained earlier, the primary function of molten cryolite (Na3AlF6) in the electrolytic extraction of aluminum is to lower the melting point of aluminum oxide (Al2O3).
Pure aluminum oxide has an extremely high melting point of around 2,050°C, which makes it impractical for electrolysis. However, when mixed with cryolite, the melting point of the mixture is significantly reduced to around 950°C, making the electrolysis process more feasible.
Additionally, the molten cryolite also acts as a solvent for aluminum oxide and increases the electrical conductivity of the electrolyte mixture, but its primary role is to lower the melting point of aluminum oxide.
So, option B "Lower the melting point of aluminum oxide" is the correct answer for the given question.
Option D is the correct answer.
The function of cryolite during the extraction of aluminum is to serve as a solvent!! Aluminum is not easy to separate from it's oxide. Cryolite is used, in the molten form, as a flux to dissolve the aluminum oxides sufficiently well to allow easy extraction.
Myschool pls I urge you to make corrections immediately.
THE CORRECT ANSWER IS B
Cryolite is used in the electrolytic extraction of aluminium to lower the melting temperature of the mixture to about 1140 K. Cryolite increases the electrical conductivity of the mixture.
In the electrolytic extraction of aluminium (Hall–Héroult process), aluminium is obtained from aluminium oxide (Al₂O₃).
Pure aluminium oxide has a very high melting point (about 2050°C).
This temperature is too high and would consume too much energy.
So, molten cryolite (Na₃AlF₆) is added to:
Lower the melting point of aluminium oxide to about 900–1000°C
Improve electrical conductivity
Help dissolve the alumina
Although cryolite also acts as a solvent, in exams like JAMB the main function tested is lowering the melting point.
So the best answer is B.
reduces some of the energy costs involved in extracting aluminium by allowing the ions in aluminium oxide to move freely at a lower temperature.
