Question

A student is given a galvanic cell consisting of a zinc electrode and a copper electrode. If the concentration of zinc ions in the zinc half-cell is 0.1 M and the concentration of copper ions in the copper half-cell is 1.0 M, what is the corrosion potential of the zinc electrode at standard conditions? (Assume that the standard electrode potential of copper is +0.34 V and that of zinc is -0.76 V.)

Answer 1

To calculate the corrosion potential of the zinc electrode, we can use the Nernst equation:E = E -  RT/nF  * ln Q where:E = corrosion potentialE = standard electrode potentialR = gas constant  8.314 J/molK T = temperature  in Kelvin, 298 K for standard conditions n = number of electrons transferred in the redox reaction  2 for both Zn and Cu F = Faraday's constant  96485 C/mol Q = reaction quotient, which is [Zn]/[Cu] for this cellFirst, we need to find the cell potential  E_cell  at standard conditions:E_cell = E Cu/Cu  - E Zn/Zn E_cell =  +0.34 V  -  -0.76 V E_cell = 1.10 VNow, we can use the Nernst equation to find the corrosion potential of the zinc electrode  E_Zn :E_Zn = E Zn/Zn  -  RT/2F  * ln [Zn]/[Cu] E_Zn = -0.76 V -   8.314 J/molK  *  298 K  /  2 * 96485 C/mol   * ln 0.1 M / 1.0 M E_Zn = -0.76 V -   8.314 * 298  /  2 * 96485   * ln 0.1 E_Zn = -0.76 V -  0.01299 V  * ln 0.1 E_Zn = -0.76 V -  0.01299 V  *  -2.303 E_Zn = -0.76 V + 0.0299 VE_Zn  -0.73 VSo, the corrosion potential of the zinc electrode at standard conditions is approximately -0.73 V.