Okay lznxl and others... Here's a question (attached) on electrolysis that kind of outlines where I'm finding things confusing. Part b) is where I'm stuck.
I've also attached the answer for part b.
I thought reduction was happening at A and C, and oxidation happening at B and D but the answer indicates otherwise.
Just focussing on A and B, I wrote that the species in the beaker were Al3+, SO4, and H2O.
Then I wrote what I thought was the four relevant half reactions and their Eo voltage value:
O2 + 4H+ + 4e- <--> 2H2O (Eo = +1.23)
SO4 + 4H+ + 2e- <--> H2SO4 + H2O (Eo = +0.17)
2H2O + 2e- <--> H2 + 2OH- (Eo = -0.83)
Al3+ + 3e- <--> Al (Eo = -1.66)
But I don't know if these are the right half reactions... And how they use them to get the answer... Which two of the four are the ones that occur and why???
Question:
Answer: