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Question

A current of 250. A flows for 24.0 hours at an anode where the reaction occurring is
Mn2+(aq) + 2H2O(l) → MnO2(s) + 4H+(aq) + 2e-
What mass of MnO2 is deposited at this anode?
19.5 kg
12.9 kg
4.87 kg
2.43 kg
none of the above

Answer 1

Charge = 250*60*60*24 = 21.6x10^6 C

Farads = 2.16x10^6/96500 = 223.83 F

So, moles of MnO2 formed = 223.83/2 = 111.915

Thus mass = (55+32)*111.915 = 9.736 kg