The standard electrode potential of a redox reaction can be determined by subtracting the standard electrode potential of the reduction half-reaction from the standard electrode potential of the oxidation half-reaction.In this case, the given reaction is already a reduction half-reaction:Fe2+ aq + 2e- -> Fe s The standard electrode potential of Fe2+ aq is +0.44 V, and the standard electrode potential of Fe s is 0 V. Since the reaction is already a reduction, we don't need to subtract any values.Therefore, the standard electrode potential of the given redox reaction at 25C is +0.44 V.