COMEDK · Chemistry · 18. Electrochemistry

The EMF of the cell \(\mathrm{Al} / \mathrm{Al}^{3+}(0.01 \mathrm{M}) \| \mathrm{Fe}^{2+}(0.02 \mathrm{M}) / \mathrm{Fe}\) is 1.209 V . The EMF of the cell can be increased by ------------------------------

A increasing the concentration of \(\mathrm{Al}^{3+}\)
B decreasing the concentration of \(\mathrm{Al}^{3+}\) and \(\mathrm{Fe}^{2+}\)
C increasing the concentration of \(\mathrm{Fe}^{2+}\)
D increasing the concentration of \(\mathrm{Al}^{3+}\) and \(\mathrm{Fe}^{2+}\)

Verified Solution

Answer & Solution

Correct Answer

(C) increasing the concentration of \(\mathrm{Fe}^{2+}\)

Step-by-step Solution

Detailed explanation

The cell reaction is \(2\mathrm{Al}(s) + 3\mathrm{Fe}^{2+}(aq) \rightarrow 2\mathrm{Al}^{3+}(aq) + 3\mathrm{Fe}(s)\). The Nernst equation for the cell EMF is given by \(E_{cell} = E^{0}_{cell} - \dfrac{0.0591}{n} \log Q\), where…

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

Explore more questions on app

From COMEDK

Explore more questions on app