JEE Main 2024 — Electrochemistry Question with Solution

To determine which galvanic cell corresponds to the given reaction:

$$\frac{1}{2}{\mathrm{H}}_{2(\mathrm{g})}+{\mathrm{AgCl}}_{(\mathrm{s})}\to {\mathrm{H}}_{(\mathrm{aq})}^{+}+{\mathrm{Cl}}_{(\mathrm{aq})}^{-}+{\mathrm{Ag}}_{(\mathrm{s})}$$

we need to examine the setups of the given cells and check if they produce the same reactants and products as in the above reaction.

Analyzing the reaction, we observe:

• Hydrogen gas ($${\mathrm{H}}_{2(\mathrm{g})}$$) is involved at one electrode and splits into $${\mathrm{H}}_{(\mathrm{aq})}^{+}$$ ions.
• Solid silver chloride ($${\mathrm{AgCl}}_{(\mathrm{s})}$$) decomposes at another electrode into $${\mathrm{Ag}}_{(\mathrm{s})}$$ and $${\mathrm{Cl}}_{(\mathrm{aq})}^{-}$$ ions.

Let's examine each option:

Option A:

$$\mathrm{Pt}\left|{\mathrm{H}}_{2(\mathrm{g})}\right|{\mathrm{HCl}}_{(\text{soln.) }}\left|{\mathrm{AgNO}}_{3(\mathrm{aq})}\right|\mathrm{Ag}$$

This cell setup does not directly involve $${\mathrm{AgCl}}_{(\mathrm{s})}$$ solid separating into $${\mathrm{Ag}}_{(\mathrm{s})}$$ and $${\mathrm{Cl}}_{(\mathrm{aq})}^{-}$$. Hence, it does not match the reaction given.

Option B:

$$\mathrm{Ag}\left|{\mathrm{AgCl}}_{(\mathrm{s})}\right|{\mathrm{KCl}}_{(\text{(soln.) }}\left|{\mathrm{AgNO}}_{3\text{ (aq.) }}\right|\mathrm{Ag}$$

This involves silver electrodes and does not have a setup for reaction with hydrogen gas or the splitting of $${\mathrm{H}}_{2(\mathrm{g})}$$ into $${\mathrm{H}}_{(\mathrm{aq})}^{+}$$ ions. So, this does not match either.

Option C:

$$\mathrm{Pt}\left|{\mathrm{H}}_{2(\mathrm{g})}\right|{\mathrm{KCl}}_{(\text{soln.) }}\left|{\mathrm{AgCl}}_{(\mathrm{s})}\right|\mathrm{Ag}$$

While this configuration includes $${\mathrm{AgCl}}_{(\mathrm{s})}$$ and $${\mathrm{H}}_{2(\mathrm{g})}$$, it uses potassium chloride solution instead of hydrochloric acid solution, which alters the chemistry and does not perfectly match the required reaction mechanism.

Option D:

$$\mathrm{Pt}\left|{\mathrm{H}}_{2(\mathrm{g})}\right|{\mathrm{HCl}}_{(\text{soln. })}\left|{\mathrm{AgCl}}_{(\mathrm{s})}\right|\mathrm{Ag}$$

This configuration fits the reaction given. Here hydrogen gas at the platinum electrode splits into $${\mathrm{H}}_{(\mathrm{aq})}^{+}$$ ions in the hydrochloric acid solution. On the other side, the solid silver chloride separates into $${\mathrm{Ag}}_{(\mathrm{s})}$$ and $${\mathrm{Cl}}_{(\mathrm{aq})}^{-}$$ ions. Hence, this accurately matches the reaction.

Therefore, the correct answer is:

Option D