COMEDK · Chemistry · 18. Electrochemistry

The standard emf of the cell \(\mathrm{Zn}\left|\mathrm{Zn}^{2+}\right|\left|\mathrm{Ag}^{+}\right| \mathrm{Ag}\) is \(1.56 \mathrm{~V}\). If the standard reduction potential of \(\mathrm{Ag}\) is \(0.8 \mathrm{~V}\), the standard oxidation potential of \(\mathrm{Zn}\) is

A \(-0.76 \mathrm{~V}\)
B \(+0.76 \mathrm{~V}\)
C \(-2.36 \mathrm{~V}\)
D \(+2.36 \mathrm{~V}\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(+0.76 \mathrm{~V}\)

Step-by-step Solution

Detailed explanation

For the cell, \(\mathrm{Zn}\left|\mathrm{Zn}^{2+} \| \mathrm{Ag}^{+}\right| \mathrm{Ag}\) \(E_{\text {cell }}^{\circ}=E_{\text {cathode }}^{\circ}-E_{\text {anode }}^{\circ}\) \(1.56 \mathrm{~V}=E_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{0}-E_{\mathrm{Zn}^{2+} / \mathrm{Zn}}^{0}\)…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match the items in Column I with their description in Column II

S.No.	Column I	S.No.	Column II
A	Kappa K	P	Intensive property.
B	\(E_{cell}^0\)	Q	Extensive property.
C	Molar conductivity	R	Decreases with decrease in concentration of both strong and weak electrolytes.
D	\(\Delta G_{cell}\)	S	Increases with dilution.

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