To calculate the standard free energy change G for the redox reaction, we first need to determine the standard cell potential Ecell for the reaction. This can be done using the Nernst equation:Ecell = E cathode - E anode In this reaction, Fe3+ is reduced to Fe2+ cathode and Sn2+ is oxidized to Sn4+ anode . Therefore, we can plug in the given values:Ecell = 0.771 V - 0.150 V = 0.621 VNow, we can use the relationship between the standard cell potential and the standard free energy change:G = -nFEcellwhere n is the number of moles of electrons transferred in the reaction, F is the Faraday constant 96,485 C/mol , and Ecell is the standard cell potential.In this reaction, 2 moles of electrons are transferred from Sn2+ to Fe3+ . So, n = 2.G = -2 * 96,485 C/mol * 0.621 VG = -119,923.77 J/molSince 1 V = 1 J/C, the units are consistent, and the standard free energy change for the reaction at 25C is:G -119,924 J/mol