NEETChemistryElectrochemistry
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For a Daniell cell at equilibrium, the standard cell potential ( E^ _ cell ) becomes zero. Reason (R): At equilibrium, the reaction quotient ( Q ) becomes equal to the equilibrium constant ( K_c ) and the cell potential ( E_ cell ) becomes zero. In the light of the above statements, choose the most
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A).
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A).
- C(A) is correct but (R) is not correct.
- D(A) is not correct but (R) is correct.
Correct answer
D. (A) is not correct but (R) is correct.
Step-by-step solution
Assertion (A) is incorrect. The standard cell potential ( E^ _ cell ) is a constant for a given cell reaction at a specific temperature. It depends only on the standard reduction potentials of the cathode and anode, not on the progress of the reaction. For a Daniell cell, E^ _ cell = 1.1 V and does not become zero at equilibrium. Reason (R) is correct. As the cell reaction proceeds, the concentrations of the reactants and products change, changing the reaction quotient ( Q ). When the cell reaches equilibrium, Q =