0 votes
59 views
in ElectroChemistry by (550 points)
Calculate the corrosion potential of a zinc-copper galvanic couple in which the zinc electrode has a concentration of 0.1 M and the copper electrode has a concentration of 0.01 M. The standard reduction potentials for Zn2+/Zn and Cu2+/Cu are -0.76 V and +0.34 V, respectively.

1 Answer

0 votes
by (330 points)
To calculate the corrosion potential of a zinc-copper galvanic couple, we can use the Nernst equation. The Nernst equation relates the reduction potential of a half-cell at non-standard conditions to the standard reduction potential, temperature, and reaction quotient.E = E -  RT/nF  * ln Q where:E = reduction potential at non-standard conditionsE = standard reduction potentialR = gas constant  8.314 J/molK T = temperature in Kelvin  assume 298 K for room temperature n = number of electrons transferred in the redox reaction  2 for both Zn and Cu redox reactions F = Faraday's constant  96485 C/mol Q = reaction quotient, which is the ratio of the concentrations of the products to the reactantsFor the zinc half-cell  oxidation :Zn s  -> Zn aq  + 2eE Zn  = -0.76 VFor the copper half-cell  reduction :Cu aq  + 2e -> Cu s E Cu  = +0.34 VThe overall reaction is:Zn s  + Cu aq  -> Zn aq  + Cu s Now, we can calculate the corrosion potential  E_corr  using the Nernst equation for both half-cells and then subtracting the two potentials.For the zinc half-cell:E Zn  = E Zn  -  RT/2F  * ln [Zn]/1 E Zn  = -0.76 -  8.314 * 298 /  2 * 96485   * ln 0.1 E Zn   -0.76 + 0.0295E Zn   -0.7305 VFor the copper half-cell:E Cu  = E Cu  -  RT/2F  * ln 1/[Cu] E Cu  = +0.34 -  8.314 * 298 /  2 * 96485   * ln 1/0.01 E Cu   +0.34 + 0.059E Cu   +0.399 VNow, we can calculate the corrosion potential  E_corr  for the zinc-copper galvanic couple:E_corr = E Cu  - E Zn E_corr = +0.399 -  -0.7305 E_corr  +1.1295 VThe corrosion potential of the zinc-copper galvanic couple is approximately +1.1295 V.

Related questions

Welcome to Sarvan Science Q&A, where you can ask questions and receive answers from other members of the community.
...