Final answer:
The standard cell potential for a Zn²⁺|Zn and Cu²⁺|Cu voltaic cell is 1.10 V when the concentrations of Zn²⁺ and Cu²⁺ are both at 1.0 M under standard conditions.
Step-by-step explanation:
The cell potential for a standard voltaic cell made of Zn²⁺|Zn and Cu²⁺|Cu electrodes can be calculated by considering the respective standard reduction potentials for each half-reaction. By convention, standard reduction potentials are always listed for a reduction reaction.
The standard cell potential (E°cell) is determined by the difference between the standard reduction potentials for zinc and copper, which has been measured as 1.10 V for the Zn/Cu system. The standard conditions assume each solution has a concentration of 1.0 M for its ions, and both electrodes are in their pure states.
Therefore, at the beginning of the reaction, when concentrations are at standard conditions, the cell potential equals the standard cell potential of 1.10 V. However, as the reaction in the cell progresses, the concentration of Zn²⁺ increases, and Cu²⁺ decreases, altering the ratio Q, which eventually leads to a change in the cell potential.