Consider an electrochemical cell involving the overall reaction at 25 oC. 2AgBr(s) + Pb(s) Pb2+ + 2Ag(s) + 2Br. Each half-reaction is carried out in a separate compartment. The anion included in the lead half-cell is NO3. The cation in the silver half-cell is K+. The two half-cells are connected by a KNO3 salt bridge. If [Pb2+] = 1.0 M, what concentration of Br ion will produce a cell emf of 0.25 V SHE at 298 K?