Question

Cell reaction is spontaneous, when:
(A) $ \text{E}_{\text{red}}^{\text{0}} $ is negative
(B) $ \text{E}_{\text{red}}^{\text{0}} $ is positive
(C) $ \text{ }\Delta\text{ }{{\text{G}}^{\text{0}}} $ is negative
(D) $ \text{ }\Delta\text{ }{{\text{G}}^{\text{0}}} $ is positive

Answer 1

Hint: The Gibbs free energy is a thermodynamic potential that can be used to calculate maximum reversible work that may be performed by a thermodynamic system at constant temperature and pressure.

Complete step by step solution:
An electrochemical cell is a device that can generate electrical energy from the chemical reactions that occur inside it. It consists of a pair of electrodes, one is the positively charged electrode or the anode at which the negative ions in the medium are discharged by giving up their electrons and the other is the negatively charged electrode or the cathode at which the cations are deposited by taking up electrons from the electrode. These two electrodes are connected to each other by an electrolyte which consists of the molten material or aqueous solution of the chemical compound that undergoes the process.
An electrochemical reaction takes place when the cations and the anions present in the electrolyte solution travel to the respective electrodes and either give up or take up electrons. As the ions travel towards, they carry a certain charge and in this process electricity is produced.
But all these processes will only be possible or be spontaneous only when the Gibbs Free energy of the medium is negative.
Hence, the correct option here is C, $ \text{ }\Delta\text{ }{{\text{G}}^{\text{0}}} $ is negative.

Note:
The Gibbs free energy is one of the most important thermodynamic factors j determining a course of a reaction. It is an important factor in determining the voltage of an electrochemical cell and the equilibrium constant for a reversible reaction.