Question

The reaction that takes place at the negative electrode (cathode) in the electrolysis of molten aluminium oxide is:
(Al^3+ + 3e^- Al)
(2O^2- O_2 + 4e^-)
(C + O_2 CO_2)
(Al_2O_3 2Al^3+ + 3O^2-)

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

An easy way to remember: RED CAT (Reduction at Cathode) and AN OX (Anode Oxidation).

Answer 1

The Correct Option is A

Step 1: Understanding Electrode Polarity: 
The negative electrode is the Cathode. Cations (positively charged ions) are attracted to the cathode to undergo reduction. 

Step 2: Identifying the Cation: 
In molten aluminium oxide (Al_2O_3), the cation is Al^3+. 

Step 3: Describing the Cathode Reaction: 
At the cathode, aluminium ions gain three electrons each to form neutral aluminium atoms: [ Al^3+ + 3e^- Al ] This is a reduction reaction. 

Step 4: Final Answer: 
Reaction 1 is the correct cathode reaction.