To calculate the exchange current density i0 for the oxidation of iron in a 0.1 M Fe2+ aq solution, we can use the Butler-Volmer equation:i0 = n * F * k0 * [Fe2+]^ 1- n * [Fe3+]^n where:- n is the number of electrons transferred in the redox reaction for Fe2+ to Fe3+, n = 1 - F is the Faraday constant 96485 C/mol - k0 is the rate constant 1.2x10^-5 cm/s - [Fe2+] is the concentration of Fe2+ ions 0.1 M - [Fe3+] is the concentration of Fe3+ ions unknown - is the transfer coefficient assumed to be 0.5 for a one-electron transfer However, we don't have the concentration of Fe3+ ions. To find it, we can use the Nernst equation:E = E0 - RT/nF * ln [Fe3+]/[Fe2+] where:- E is the electrode potential unknown - E0 is the standard electrode potential +0.77 V - R is the gas constant 8.314 J/mol*K - T is the temperature in Kelvin 25C = 298.15 K Since we are dealing with the equilibrium state, E = 0 V. Rearranging the Nernst equation to solve for [Fe3+], we get:0 = 0.77 - 8.314 * 298.15 / 96485 * ln [Fe3+]/0.1 0.77 = 8.314 * 298.15 / 96485 * ln [Fe3+]/0.1 Now, we can solve for [Fe3+]:ln [Fe3+]/0.1 = 0.77 * 96485 / 8.314 * 298.15 [Fe3+] = 0.1 * exp 0.77 * 96485 / 8.314 * 298.15 [Fe3+] 0.1 * exp 24.96 1.95x10^10 MNow that we have the concentration of Fe3+ ions, we can calculate the exchange current density using the Butler-Volmer equation:i0 = 1 * 96485 * 1.2x10^-5 * 0.1 ^ 1-0.5 1 * 1.95x10^10 ^0.5*1 i0 96485 * 1.2x10^-5 * 0.1 * sqrt 1.95x10^10 i0 1.15782 A/cmSo, the exchange current density for the oxidation of iron in a 0.1 M Fe2+ aq solution at 25C is approximately 1.15782 A/cm.