Medium MCQ +4 / -1 PYQ · JEE Mains 2023

The reaction

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

occurs in which of the given galvanic cell.

  1. A $$\mathrm{Ag}|\mathrm{AgCl}(\mathrm{s})| \mathrm{KCl}\left(\mathrm{sol}^{\mathrm{n}}\right)\left|\mathrm{AgNO}_{3}\right| \mathrm{Ag}$$
  2. B $$\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{HCl}\left(\mathrm{sol}^{\mathrm{n}}\right)|\mathrm{AgCl}(\mathrm{s})| \mathrm{Ag}$$ Correct answer
  3. C $$\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{HCl}\left(\mathrm{sol}^{\mathrm{n}}\right)\left|\mathrm{AgNO}_{3}\left(\mathrm{sol}^{\mathrm{n}}\right)\right| \mathrm{Ag}$$
  4. D $$\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{KCl}\left(\mathrm{sol}^{\mathrm{n}}\right)|\mathrm{AgCl}(\mathrm{s})| \mathrm{Ag}$$

Solution

<p>The provided reaction is:</p> <p>$$\frac{1}{2} \mathrm{H}_{2}(\mathrm{~g})+\mathrm{AgCl}(\mathrm{s}) \rightleftharpoons \mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s})$$</p> <p>This reaction involves the following half-reactions:</p> <ol> <li>Oxidation of hydrogen gas to H+ ions: $$\frac{1}{2} \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{H}^{+}(\mathrm{aq}) + e^-$$</li><br/> <li>Reduction of AgCl to Ag: $$\mathrm{AgCl}(\mathrm{s}) + e^- \rightleftharpoons \mathrm{Ag}(\mathrm{s}) + \mathrm{Cl}^{-}(\mathrm{aq})$$</li> </ol> <p>Looking at the options provided:</p> <p>Option A: Doesn&#39;t involve H<sub>2</sub> gas, so it can&#39;t be correct.</p> <p>Option B: This includes the necessary elements - H<sub>2</sub>, AgCl, and Ag. </p> <p>Option C: Doesn&#39;t involve AgCl, so it can&#39;t be correct.</p> <p>Option D: Also includes the necessary elements - H<sub>2</sub>, AgCl, and Ag.</p> <p>However, looking closely, we can see that Option B represents the galvanic cell for this reaction. The reaction requires the oxidation of H<sub>2</sub> to H<sup>+</sup>, which occurs at the anode. The reaction also requires the reduction of AgCl to Ag and Cl-, which occurs at the cathode.</p> <p>In Option B, the anode (on the left) is where H<sub>2</sub> is being oxidized to H<sup>+</sup>. The cathode (on the right) is where AgCl is reduced to Ag and Cl<sup>-</sup>. The salt bridge or ion exchange component is HCl, which allows for the flow of ions to balance charge in the cell.</p> <p>Therefore, the reaction occurs in the galvanic cell represented by Option B.</p>

About this question

Subject: Chemistry · Chapter: Electrochemistry · Topic: Electrochemical Cells

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