Question

Mark the false statement
A.A salt bridge is used to eliminate liquid junction potential.
B.The Gibbs free energy change, $\Delta G$ is related with electromotive force (E) as \[\Delta G=-nFE.\]
C.Nernst equation for single electrode potential is \[E=Eo-\dfrac{RT}{nF}log{{a}_{{{M}^{n+}}}}.\]
D.The efficiency of a hydrogen-oxygen fuel cell is \[23\%.\]

Answer 1

Hint: We know that this question gives knowledge about the Nernst equation. Nernst equation helps in determining the cell potential under various conditions. Also helps in determining the electrode potential. Usually, the reaction involves an oxidant and a reluctant, so for a single electrode potential, only one part of the reaction is present.

Complete answer:
When a metal electrode is dipped in its solution, then the electrode has the tendency to either lose an electron or gain electrons, so this tendency is known as Electrode potential. Nernst equation helps in determining the cell potential under various non-standard conditions. Also helps in determining the electrode potential. Nernst equation helps in determining the relation between reduction potential or oxidation potential of an electrochemical cell reaction to the temperature, activities and standard electrode potential of the chemical species. Single electrode potential is defined as the potential generated when the metal is dipped in the solution consisting of its own ions, at the interphase between solution and metal. Apparently, it is not possible to determine the single electrode potential because the half-cell reactions do not occur independently. Any reference should always be provided.
\[E=Eo+\dfrac{2.303RT}{nF}log{{a}_{{{M}^{n+}}}}.\]
Where E is the electrode potential of the substance, is the standard electrode potential, R is the gas constant, T is the temperature, n is the number of electrons involved in the reaction, F is the Faraday’s constant and Q is the ratio of the concentration of the ions involved in the reaction.
Therefore, the correct answer is option C.

Note:
Remember to always remember the values of all the constants. Nernst's equation should be remembered carefully. And also remember whenever it is positive the reaction becomes non- spontaneous and the cell stops working.