Question

Calculate the potential of a zinc electrode immersed in 0.0200 M in NaOH and saturated with

Zn(OH)2 (E0=Zn2+ / Zn: -0.763 V, Ksp: 3×10-16)

Answer 1

Zn(OH)₂ = Zn²⁺ + 2OH^-

[Zn²⁺] = K_sp / [OH^-]² = 3x10^-16 / (0.0200)² = 7.5x10^-13 M

Zn²⁺ + 2e = Zn

E = -0.763 - 0.0592/2 x log(1/7.5x10^-13) = -1.09 V