Galvanic cells Knowledge-Based Download PDF

Questions

1. 1.

   In a galvanic cell containing a half-cell composed of an aqueous mixture of iron(II) and iron(III) ions, an inert platinum electrode is utilized. Which of the following correctly describes the primary role of the platinum electrode in this half-cell?

   • A) It undergoes spontaneous oxidation to release platinum ions into the electrolyte and supply electrons to the circuit.
   • B) It provides a chemically stable conductive surface for electron transfer without participating in the redox reaction.
   • C) It continuously dissolves into the solution to maintain electrical neutrality between the two half-cells.
   • D) It acts as a semipermeable barrier that prevents iron ions from diffusing into the salt bridge.
2. 2.

   Which of the following statements correctly describes a galvanic cell that has discharged until it reaches chemical equilibrium?

   • A) The standard cell potential ($E^\circ_{\text{cell}}$) decreases to zero, while the reaction quotient remains less than the equilibrium constant ($Q < K$).
   • B) The cell potential ($E_{\text{cell}}$) equals the standard cell potential ($E^\circ_{\text{cell}}$), allowing electrical current to flow continuously at a constant rate.
   • C) The cell potential ($E_{\text{cell}}$) decreases to zero because the reaction quotient equals the equilibrium constant ($Q = K$), and no net current flows.
   • D) The reaction quotient exceeds the equilibrium constant ($Q > K$), which causes the direction of spontaneous electron flow in the external circuit to reverse.
3. 3.

   In an operating galvanic cell under standard conditions, which statement correctly identifies the electrical polarity of the anode along with the signs of the standard cell potential ($E^\circ_{\text{cell}}$) and standard Gibbs free energy change ($\Delta G^\circ$)?

   • A) The anode is positive, $E^\circ_{\text{cell}} < 0$, and $\Delta G^\circ < 0$.
   • B) The anode is positive, $E^\circ_{\text{cell}} > 0$, and $\Delta G^\circ > 0$.
   • C) The anode is negative, $E^\circ_{\text{cell}} < 0$, and $\Delta G^\circ > 0$.
   • D) The anode is negative, $E^\circ_{\text{cell}} > 0$, and $\Delta G^\circ < 0$.
4. 4.

   Which of the following statements correctly describes the energy transformation and electrode processes in an operating galvanic cell?

   • A) An external electrical source drives a nonspontaneous redox reaction, with oxidation occurring at the positive cathode.
   • B) Electrical energy is consumed to drive a spontaneous redox reaction, causing the anode to serve as the positive terminal.
   • C) Chemical energy is converted into electrical energy by a spontaneous redox reaction, with reduction taking place at the negative anode.
   • D) Chemical energy is converted into electrical energy by a spontaneous redox reaction, with oxidation taking place at the negative anode.
5. 5.

   In an operating standard galvanic cell composed of a zinc electrode in $1\text{ M Zn(NO}_3)_2$ and a copper electrode in $1\text{ M Cu(NO}_3)_2$ linked by a potassium nitrate ($\text{KNO}_3$) salt bridge, which statement correctly describes the movement of charged species during spontaneous discharge?

   • A) Electrons flow from the copper electrode to the zinc electrode through the external wire.
   • B) Potassium ions migrate into the copper half-cell while nitrate ions migrate into the zinc half-cell through the salt bridge.
   • C) Zinc cations migrate through the salt bridge to deposit directly onto the surface of the copper cathode.
   • D) Nitrate ions migrate into the copper half-cell to balance excess copper cations generated during the reaction.