Under standard conditions for all concentrations, the following reaction is spontaneous at 25oC. O2(g) + 4H+(aq) +

Question:

Under standard conditions for all concentrations, the following reaction is spontaneous at 25oC.
O2(g) + 4H+(aq) + 4Br (aq) → 2H2O(l) + 2Br2(l)
If [H+] is adjusted by adding a buffer of 0.10 M NaOCN and 0.10 M HOCN (Ka = 3.5 × 10 4), what value will Ecell have, and will the reaction be spontaneous at this [H+]?