To calculate the standard free energy change G for the redox reaction, we first need to determine the overall cell potential Ecell for the reaction. We can do this by subtracting the standard reduction potential of the half-reaction being oxidized from the standard reduction potential of the half-reaction being reduced.In this case, the half-reactions are:Fe^3+ aq + e^- --> Fe^2+ aq E = +0.771 V reduction 2H^+ aq + 2e^- --> H2 g E = 0.000 V oxidation Since the H2 g is being oxidized to 2H^+ aq , we need to reverse the second half-reaction:H2 g --> 2H^+ aq + 2e^- E = -0.000 V oxidation Now, we can calculate the overall cell potential Ecell :Ecell = E reduction - E oxidation Ecell = 0.771 V - -0.000 V Ecell = 0.771 VNext, we can use the relationship between the standard free energy change G , the overall cell potential Ecell , and the number of moles of electrons transferred n in the reaction:G = -n * F * Ecellwhere F is the Faraday constant 96,485 C/mol .In this reaction, 2 moles of electrons are transferred from H2 to 2Fe^3+ . So, n = 2.Now, we can calculate G:G = -2 * 96,485 C/mol * 0.771 VG = -148,995.77 J/molSince the standard free energy change is typically expressed in kJ/mol, we can convert this value:G = -148.995 kJ/molSo, the standard free energy change for the redox reaction is -148.995 kJ/mol.