In the given electrochemical cell, Ag ( s )| AgCl ( s )| FeCl _ 2 ( aq ), FeCl _ 3 ( aq ) Pt ( s ) at 298 K, the cell potential ( E _ cell ) will increase when : A. Concentration of Fe ^ 2+ is increased. B. Concentration of Fe ^ 3+ is decreased. C. Concentration of Fe ^ 2+ is decreased. D. Concentration of Fe ^ 3+ is increased. E. Concentration of Cl ^ - is increased. Choose the correct answer from the options given below :
C. C, D and E Only
The cell Ag(s)|AgCl(s)|FeCl₂(aq), FeCl₃(aq)|Pt(s) has the reaction: Ag(s) + Cl⁻ + Fe³⁺ → AgCl(s) + Fe²⁺ Using Nernst equation: E_ cell = E°_ cell - 0.059 n Q where Q = [Fe^ 2+ ] [Fe^ 3+ ][Cl^-] For E_ cell to increase, Q must decrease. Analyzing each condition: A. Increase [Fe²⁺] increases Q, decreases E_ cell - false B. Decrease [Fe³⁺] increases Q (smaller denominator), decreases E_ cell - false C. Decrease [Fe²⁺] decreases Q, increases E_ cell - true D. Increase [Fe³⁺] decreases Q, increases E_ cell - true E. Increase [Cl⁻] decreases Q, increases E_ cell - true Therefore C, D, and E cause E_ cell to increase.
Related: Chemistry — Electrochemistry · All PYQ Banks