Question

Consider the following half-reactions:

(1) CuI(s) + e - → Cu (s) + I - (aq) E°red = -0.185 V

(2) Cu+ (aq) + e - → Cu (s) E°red = +0.521V

Calculate Ksp for CuI based on this information.

Answer 1

The chemical equation for CuI

CuI_(s) = Cu⁺+I^-

So K_SP = [Cu⁺][I^-]

So equations are used:

CuI_(s)+e^- = Cu_(s)+I^-_(aq)  E⁰_red = -0.185 V

Cu_(s) = Cu⁺_(aq0+e^- E⁰_red = -0.521V (reaction in reverse direction so sign changed )

So merging these two reactions

CuI_(s) = Cu⁺+I^-   E⁰_red = -0.706 V

Now use the Nernst Equation

Here n= no of electron=1

When cell is in equilibrium then E_cell = 0 V

So put all value in equation

so log K = -11.95

So K=K_SP=1.12* 10^-12