Question

Calculate the Gibbs free energy change for the electrochemical reaction in which 2 moles of electrons are transferred from a zinc electrode to a copper electrode. The standard reduction potentials are E°(Cu²⁺/Cu) = 0.34 V and E°(Zn²⁺/Zn) = -0.76 V. What is the spontaneity of the reaction under standard conditions?

Answer 1

To calculate the Gibbs free energy change  G  for the electrochemical reaction, we first need to determine the standard cell potential  Ecell  for the reaction. The standard cell potential can be calculated using the standard reduction potentials of the two half-reactions:Ecell = E Cu/Cu  - E Zn/Zn Ecell = 0.34 V -  -0.76 V  = 1.10 VNow that we have the standard cell potential, we can calculate the Gibbs free energy change using the following equation:G = -nFEcellwhere n is the number of moles of electrons transferred  2 moles in this case , F is the Faraday's constant  96,485 C/mol , and Ecell is the standard cell potential.G = -2 mol  96,485 C/mol  1.10 VG = -212,667 J/molSince the Gibbs free energy change  G  is negative, the reaction is spontaneous under standard conditions.