The standard potential for the cell
Cl₂(g) + Cu(s) ⇌ CuCl₂(aq)
Is +1.02 V. Determine the potential of the cell at a temperature of 298 K when the partial pressure of chlorine, Cl₂, gas is 0.100 bar and the concentration of copper (II) chloride, CuCl₂, is 0.017 mol dm^-3.

Question

Quizplus · Accepted Answer

The Nernst equation is used to calculate the potential of an electrochemical cell under non-standard conditions. The equation is E = E° - (RT/nF)lnQ, where E is the cell potential under non-standard conditions, E° is the standard cell potential, R is the gas constant (8.314 J/mol·K), T is the temperature in Kelvin, n is the number of moles of electrons transferred in the reaction, F is the Faraday constant (96485 C/mol), and Q is the reaction quotient. Given that the standard potential (E°) is +1.02 V, the temperature (T) is 298 K, the partial pressure of Cl2 is 0.100 bar (which can be used directly in Q since the standard state is 1 bar), and the concentration of CuCl2 is 0.017 M, we can calculate the cell potential under these conditions. Since the reaction involves the transfer of 2 electrons (from Cu to Cu^2+), n = 2. The reaction quotient Q can be calculated based on the given concentrations and pressures. Without doing the exact calculation, the answer is not the standard potential (+1.02 V) but is adjusted based on these conditions. The correct answer involves applying the Nernst equation with the given values, which results in a potential different from the standard potential, indicating B) +1.13 V as the correct choice based on the provided options and the direction of change implied by the conditions (higher concentration of products or lower partial pressure of reactants would increase the cell potential).

The Standard Potential for the Cell