To calculate the standard Gibbs free energy change, we first need to determine the cell potential E_cell under non-standard conditions using the Nernst equation:E_cell = E_cell - RT/nF * ln Q where E_cell is the standard cell potential, R is the gas constant 8.314 J/molK , T is the temperature in Kelvin assuming 298 K , n is the number of moles of electrons transferred in the redox reaction, F is the Faraday constant 96,485 C/mol , and Q is the reaction quotient.First, let's find the standard cell potential E_cell :E_cell = E_cathode - E_anodeE_cell = +0.80 V - -0.25 V = 1.05 VNow, let's find the reaction quotient Q :Q = [Ni2+]/[Ag+]Q = 0.010 M / 0.20 M = 0.05The balanced redox reaction is:Ni2+ + 2Ag Ni + 2Ag+So, n = 2 moles of electrons are transferred in the reaction.Now, we can use the Nernst equation to find E_cell:E_cell = 1.05 V - 8.314 J/molK * 298 K / 2 * 96,485 C/mol * ln 0.05 E_cell = 1.05 V - 0.0257 V * ln 0.05 E_cell 1.05 V - 0.0257 V * -2.9957 E_cell 1.05 V + 0.077 VE_cell 1.127 VFinally, we can calculate the standard Gibbs free energy change G using the following equation:G = -nFE_cellG = -2 * 96,485 C/mol * 1.127 VG -217,000 J/molSo, the standard Gibbs free energy change for the reaction is approximately -217 kJ/mol.