Cell potential Knowledge-Based Download PDF

Questions

1. 1.

   In an operating galvanic cell based on the reaction $\text{Zn}(s) + \text{Cu}^{2+}(aq) \rightarrow \text{Zn}^{2+}(aq) + \text{Cu}(s)$, which of the following modifications will increase the cell potential ($E_{\text{cell}}$) at 298 K?

   • A) Increasing the concentration of $\text{Cu}^{2+}(aq)$ ions in the cathode compartment
   • B) Increasing the concentration of $\text{Zn}^{2+}(aq)$ ions in the anode compartment
   • C) Increasing the mass of the solid zinc electrode
   • D) Increasing the mass of the solid copper electrode
2. 2.

   Which of the following statements correctly describes the cell potential of an operating galvanic cell when the redox reaction reaches chemical equilibrium?

   • A) Both $E_{\text{cell}}$ and $E^\circ_{\text{cell}}$ become zero.
   • B) $E_{\text{cell}}$ reaches its maximum value, whereas $E^\circ_{\text{cell}}$ becomes zero.
   • C) $E_{\text{cell}}$ becomes zero, whereas $E^\circ_{\text{cell}}$ remains unchanged.
   • D) $E_{\text{cell}}$ equals $E^\circ_{\text{cell}}$, and the reaction quotient $Q$ equals 1.
3. 3.

   When balancing an oxidation-reduction reaction, the stoichiometric coefficients of a half-reaction are multiplied by an integer. Which of the following statements correctly explains how this modification affects the standard reduction potential ($E^\circ$) of that half-reaction?

   • A) The value of $E^\circ$ is multiplied by the integer because the total electrical work performed increases proportionally with stoichiometric quantity.
   • B) The value of $E^\circ$ remains unchanged because standard reduction potential is an intensive property defined as potential energy per unit charge.
   • C) The value of $E^\circ$ increases exponentially because multiplying stoichiometric coefficients raises the equilibrium constant to that power.
   • D) The value of $E^\circ$ is divided by the integer because the driving force is distributed over a greater number of moles of reactant.
4. 4.

   Which of the following statements correctly describes the relationship between the standard cell potential ($E^\circ_{\text{cell}}$), the standard Gibbs free energy change ($\Delta G^\circ$), and the spontaneity of an electrochemical reaction under standard conditions?

   • A) A positive $E^\circ_{\text{cell}}$ corresponds to a negative $\Delta G^\circ$, signifying a thermodynamically spontaneous reaction under standard conditions.
   • B) A positive $E^\circ_{\text{cell}}$ corresponds to a positive $\Delta G^\circ$, signifying a thermodynamically spontaneous reaction under standard conditions.
   • C) A negative $E^\circ_{\text{cell}}$ corresponds to a negative $\Delta G^\circ$, signifying a thermodynamically nonspontaneous reaction under standard conditions.
   • D) A zero $E^\circ_{\text{cell}}$ corresponds to a negative $\Delta G^\circ$, signifying that the cell reaction is at dynamic equilibrium.
5. 5.

   A standard galvanic cell is constructed using the following half-reactions: $\text{Ni}^{2+}(aq) + 2e^- \rightarrow \text{Ni}(s) \quad E^\circ = -0.25\text{ V}$ $\text{Ag}^{+}(aq) + e^- \rightarrow \text{Ag}(s) \quad E^\circ = +0.80\text{ V}$ What is the standard cell potential ($E^\circ_{\text{cell}}$) for this electrochemical cell?

   • A) +0.55 V
   • B) +1.05 V
   • C) -1.05 V
   • D) +1.35 V