A galvanic cell is constructed using a Cu(s) | Cu2+(aq) half-cell and a Zn(s) |…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A galvanic cell is constructed using a Cu(s) | Cu2+(aq) half-cell and a Zn(s) | Zn2+(aq) half-cell. Both ionic solutions are initially 0.010 M, and the cell is operated at two different temperatures while the concentrations are held constant.
Copper half-reaction (as written for reduction): Cu2+(aq) + 2 e− → Cu(s)
Zinc half-reaction (as written for reduction): Zn2+(aq) + 2 e− → Zn(s)
The standard cell potential is 1.10 V at 298 K.
Answer the following questions, elaborating your reasoning with clear, well-organized chemical arguments.
(a) Predict qualitatively whether the measured cell potential will increase, decrease, or remain unchanged when the temperature is raised from 298 K to 338 K while all solution concentrations remain at 0.010 M. Justify your prediction without performing any numerical calculation.
(b) Describe, at the particulate level, how increasing temperature affects the relative importance of the energetic and entropic terms that govern the driving force for this redox process.
(c) Explain why the numerical value of the standard potential is often treated as temperature-independent over moderate temperature ranges, whereas the measured non-standard potential is not.