Multiple Choice
What is the standard cell potential (E°_cell) for the voltaic cell represented by the following cell diagram? Pt | H2(g, 1 atm) | 0.0025 M HCl || H+ (1 M) | H2(g, 1 atm) | Pt
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20. Electrochemistry
Cell Potential: Standard
Multiple Choice
Calculate the standard cell potential of an electrolytic cell when given the following half reactions.
Standard Reduction Potentials
Fe3+ (aq) + e – → Fe2+ (aq) E°red = + 0.769 V
Li+ (aq) + e – → Li (s) E°red = – 3.04 V
A
–2.271 V
B
–1.551 V
C
–3.060 V
D
–3.809 V
Verified step by step guidance1
Identify the two half-reactions given: Fe3+ (aq) + e⁻ → Fe2+ (aq) with E°red = +0.769 V and Li+ (aq) + e⁻ → Li (s) with E°red = -3.04 V.
Determine which half-reaction will be the oxidation and which will be the reduction. The half-reaction with the more positive reduction potential will proceed as the reduction. Therefore, Fe3+ (aq) + e⁻ → Fe2+ (aq) is the reduction reaction.
Reverse the half-reaction with the less positive (or more negative) reduction potential to represent the oxidation process. Thus, Li (s) → Li+ (aq) + e⁻ with E°ox = +3.04 V.
Calculate the standard cell potential (E°cell) using the formula: E°cell = E°red (cathode) - E°ox (anode). Substitute the values: E°cell = 0.769 V - 3.04 V.
Perform the subtraction to find the standard cell potential, ensuring to keep track of the sign, which indicates the direction of electron flow in the cell.
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