Question

Calculate the standard free energy change (ΔG°) for the following redox reaction at 298 K, given that E°cell = 0.91 V:Zn(s) + 2 Ag+(aq) → Zn2+(aq) + 2 Ag(s)

Answer 1

To calculate the standard free energy change  G  for the given redox reaction, we can use the following equation:G = -nFEcellwhere:G = standard free energy changen = number of moles of electrons transferred in the redox reactionF = Faraday's constant  96,485 C/mol Ecell = standard cell potentialFirst, we need to determine the number of moles of electrons transferred in the redox reaction. In this case, the balanced redox reaction is:Zn s  + 2 Ag+ aq   Zn2+ aq  + 2 Ag s The zinc atom loses 2 electrons  oxidation  and each silver ion gains 1 electron  reduction . Since there are 2 silver ions involved, a total of 2 moles of electrons are transferred.Now we can plug the values into the equation:G = -  2 mol   96,485 C/mol   0.91 V G = -  2   96,485   0.91 G = -175,763.7 J/molSince the standard free energy change is usually expressed in kJ/mol, we can convert the value:G = -175.76 kJ/molSo, the standard free energy change  G  for the given redox reaction at 298 K is -175.76 kJ/mol.