Question

Calculate the standard free energy change (ΔG°) for the redox reaction:Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s) Given that the standard reduction potentials of Cu2+(aq)/Cu(s) and Ag+(aq)/Ag(s) are +0.34V and +0.80V, respectively.

Answer 1

To calculate the standard free energy change  G  for the redox reaction, we first need to determine the overall cell potential  E  for the reaction. We can do this by subtracting the standard reduction potential of the oxidation half-reaction from the standard reduction potential of the reduction half-reaction.In this case, the reduction half-reaction is:2Ag+ aq  + 2e-  2Ag s  with E = +0.80VThe oxidation half-reaction is:Cu s   Cu2+ aq  + 2e- with E = -0.34V  we change the sign because it's an oxidation reaction Now, we can calculate the overall cell potential  E  for the reaction:E = E reduction  - E oxidation  = +0.80V -  -0.34V  = +1.14VNext, we can use the relationship between the standard free energy change  G , the overall cell potential  E , and the number of moles of electrons transferred  n  in the reaction:G = -nFEwhere F is the Faraday constant, which is approximately 96,485 C/mol.In this reaction, 2 moles of electrons are transferred  from Cu to 2Ag+ . So, n = 2.Now, we can calculate G:G = -2 * 96,485 C/mol * 1.14V = -219,664.6 J/molSince the standard free energy change is usually expressed in kJ/mol, we can convert it:G = -219.7 kJ/mol