To calculate the standard free energy change G for the given redox reaction, we can use the Nernst equation:G = -nFEwhere n is the number of electrons transferred in the reaction, F is the Faraday constant 96,485 C/mol , and E is the standard cell potential.First, we need to determine the number of electrons transferred in the reaction. In this case, the reaction involves the transfer of 6 electrons.Next, we need to determine the standard cell potential E for the reaction. Since we are given the standard reduction potentials for both half-reactions, we can calculate the overall cell potential by adding them together:E Cr2O7 2- /Cr 3+ = 1.33 VE H2O/O2 = -0.82 VE cell = E Cr2O7 2- /Cr 3+ + E H2O/O2 = 1.33 V + -0.82 V = 0.51 VNow we can calculate the standard free energy change G :G = -nFE = -6 mol * 96,485 C/mol * 0.51 V = -295,861.9 J/molSince we typically express free energy changes in kJ/mol, we can convert this value:G = -295,861.9 J/mol * 1 kJ/1000 J = -295.86 kJ/molSo, the standard free energy change for the given redox reaction at 298 K is -295.86 kJ/mol.