Question

Use standard reduction potentials to calculate the standard free energy change in kJ for the reaction: Ni2 (aq) Cd(s) Ni(s) Cd2 (aq) Answer: -29.529 kJ K for this reaction would be than one.

Answer 1

Answer:

ΔGº = --29 kJ

Explanation:

The equation to use is ΔGº = -nFEºcell

where n is the number of mole of electrons exchanged in the redox equation

           F is Faraday´s constant 96485 C/mole

           Eº  cell potential

Ni²⁺(aq) + 2e⁻    ⇒  Ni (s)    Eºred = -0.25 V

Cd(s)  ⇒  Cd²⁺ + 2e⁻           Eºox   = +0.40 V

Eºcell = 0.40 V -0.25 V = 0.15 V

ΔGº = - 2 mole x 96485 C/mol x 0.15 V =  -2.9 x 10⁴J = -29 kJ

(remember 1 Coulomb x 1 Volt = 1 Joule)