The following electrochemical cell has been set up: ; V; V. If an ammeter is connected between the t — Electrochemistry Chemistry Question
Question
The following electrochemical cell has been set up: $Pt(s)\|Fe^{3+}, Fe^{2+} (a = 1) \|\| Ce^{4+}, Ce^{3+} (a = 1) \| Pt(s)$; $E^\circ (Fe^{3+}\|Fe^{2+}) = 0.77$ V; $E^\circ (Ce^{4+}\|Ce^{3+}) = 1.61$ V. If an ammeter is connected between the two platinum electrodes, predict the direction of flow of current. Will the current increase or decrease with time?
💡 Solution & Explanation
Since the $Ce^{4+}/Ce^{3+}$ couple has a higher reduction potential, it acts as the cathode (reduction), and the $Fe^{3+}/Fe^{2+}$ couple acts as the anode (oxidation). Electrons flow from anode (Fe) to cathode (Ce). Conventional current flows in the opposite direction, from the Ce electrode to the Fe electrode. As the reaction proceeds towards equilibrium, the driving force (voltage) drops, so the current decreases with time. Therefore, correct answer is A.