To calculate the Gibbs free energy change G for the reaction, we first need to determine the overall cell potential E for the reaction. This can be done by adding the standard electrode potentials for the two half-reactions:E Fe3+ aq + e- Fe2+ aq = -0.77 VE Cl2 g + 2e- 2Cl- aq = 1.36 VSince the Fe3+/Fe2+ half-reaction needs to be reversed to match the overall reaction, we need to change the sign of its potential:E Fe2+ aq Fe3+ aq + e- = 0.77 VNow, we can add the potentials for the two half-reactions:E overall = E Fe2+ aq Fe3+ aq + e- + E Cl2 g + 2e- 2Cl- aq E overall = 0.77 V + 1.36 VE overall = 2.13 VNext, we can use the Nernst equation to calculate the Gibbs free energy change G :G = -nFEwhere n is the number of moles of electrons transferred in the reaction in this case, 2 and F is the Faraday constant approximately 96,485 C/mol .G = -2 * 96,485 C/mol * 2.13 VG = -411,032 J/molSo, the Gibbs free energy change G for the reaction at 298 K is -411,032 J/mol.