Write the overall reaction taking place in the process used for the electrolysis of alumina by Hall- Heroult process.

Explanation

To write the overall reaction taking place in the Hall-Héroult process for the electrolysis of alumina (Al₂O₃), we need to consider the reactions occurring at both the cathode and the anode.

### Step-by-Step Solution:

1. **Identify the Electrolyte**: The Hall-Héroult process uses alumina (Al₂O₃) dissolved in molten cryolite (Na₃AlF₆) as the electrolyte.

2. **Cathode Reaction**: At the cathode, aluminum ions (Al³⁺) are reduced to form aluminum metal (Al). The half-reaction at the cathode can be written as:
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