Q1: The Al₂ O₃ content of cryolite in Hall-Heroult's cell is maintained between __________ percent.

ANS:A - 2-5

The correct range for the Al2O3 content of cryolite in Hall-Heroult's cell is typically between 2-5 percent. Let me explain further: In the Hall-Heroult process, cryolite (Na3AlF6) is used as a solvent to dissolve alumina (Al2O3) during the electrolytic production of aluminum. The addition of cryolite helps to lower the melting point of alumina, reducing the energy required for the electrolysis process. However, only a small percentage of alumina is dissolved in the cryolite bath. This is because the solubility of alumina in cryolite is limited, and adding too much alumina can lead to various operational issues, such as increased energy consumption, decreased efficiency, and the formation of undesirable by-products. Therefore, to ensure efficient operation of the Hall-Heroult process, it is essential to maintain the Al2O3 content of cryolite within a specific range. This range typically falls between 2-5 percent Al2O3 concentration in the cryolite bath. This concentration allows for effective dissolution of alumina while minimizing the negative effects associated with excessive alumina content. In summary, the Al2O3 content of cryolite in the Hall-Heroult process is typically maintained between 2-5 percent to optimize the efficiency and performance of the electrolytic production of aluminum.