Answer:
1. 0.559 V
2. 0.514 V
Explanation:
Nernst Equation - Can be used to find the cell potential at any moment in during a reaction or at conditions other than standard-state.
E = E₁ - RT/nF ㏑Q
E = cell potential (V) under specific conditions
E₁= cell potential at standard-state conditions
R = ideal gas constant = 8.314 J/mol-K
T = temperature (kelvin), which is generally 25C (298 K)
n = number of moles of electrons transferred in the balanced equation
F = Faraday's constant, the charge on a mole of electrons = 95,484.56 C/mol
lnQ = the natural log of the reaction quotient at the moment in time
First calculate E₀ for the cell.
Zn(s) ==> Zn²⁺(aq) + 2e⁻ . . .E₀ = +0.76 V
Ni⁺²(aq) + 2e⁻ ==> Ni(s) . . . E₀ = -0.23 V
Zn(s) + Ni⁺²(aq) ==> Zn⁺²(aq) + Ni(s) . .E₀ cell = +0.53 V
Then use the Nernst equation:
E cell = E₀ cell - 0.059/n log Q = 0.53 - 0.059/2 log ([Zn⁺²]/[Ni⁺²]) = 0.53 - 0.0295 log (0.200/2.0) = 0.559 V
For the second set of conditions,
E cell = 0.53 - 0.0295 log (0.999/0.290) = 0.514 V