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During the electrolysis of molten aluminium oxide to produce aluminium, using carbon electrodes,
two consecutive reactions occur at the anode, each producing a different gas.
How does the oxidation number of oxygen change in these reactions?
A decreases by 2, then increases by 2
B increases by 2, then decreases by 2
C increases by 2, then decreases by 4
D no change, then decreases by 2
A Because the two consecutive reactions in anode could possibly be:
1. 2C + O2 -> 2CO
2. 2CO + O2 -> 2CO2
The oxidation state of O2 in CO is -2
And oxidation state of O2 in CO2 is -4
It is a pretty confusing question, considering decreases as subtraction and increases as addition, Else it is easy.