객관식
Which of the following represents the balanced equation for the overall redox reaction between Fe³⁺(aq) and Cr(s) based on their standard reduction potentials?
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20. Electrochemistry
Standard Reduction Potentials
객관식
Use the table of standard reduction potentials to calculate the equilibrium constant at standard temperature (25 °C) for the reaction: Fe(s) + Ni²⁺(aq) → Fe²⁺(aq) + Ni(s). Which of the following is the correct equilibrium constant (K)?
A
K = 1.0 x 10^1
B
K = 1.0 x 10^3
C
K = 1.0 x 10^2
D
K = 1.0 x 10^5
검증된 단계별 안내1
Identify the half-reactions involved in the given redox reaction. The oxidation half-reaction is Fe(s) → Fe²⁺(aq) + 2e⁻, and the reduction half-reaction is Ni²⁺(aq) + 2e⁻ → Ni(s).
Look up the standard reduction potentials (E°) for each half-reaction from the table of standard reduction potentials. The standard reduction potential for Ni²⁺(aq) + 2e⁻ → Ni(s) is typically given, as well as for Fe²⁺(aq) + 2e⁻ → Fe(s).
Calculate the standard cell potential (E°cell) using the formula: E°cell = E°(reduction) - E°(oxidation). Substitute the values from the table to find E°cell.
Use the Nernst equation to relate the standard cell potential to the equilibrium constant (K). The equation is: ln(K) = (nF * E°cell) / (RT), where n is the number of moles of electrons transferred, F is Faraday's constant (96485 C/mol), R is the universal gas constant (8.314 J/mol·K), and T is the temperature in Kelvin (298 K for standard conditions).
Solve for K by rearranging the Nernst equation to K = e^((nF * E°cell) / (RT)). Calculate the exponent using the values for n, F, E°cell, R, and T, and then find K by taking the exponential of the result.
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