Numerical

Using the E° values of A and B, predict which is better for coating the surface of iron [E°(Fe^{+2}/Fe) = -0.44V] to prevent corrosion and why?

Given: E° (A^{+2}/A)=-2.37 V: E°(B^{+2}/B)= -0.14V

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#### Solution

Given:

E°(A^{+}2 / A) = 2.37 V

E°(B^{+2} / B) = -0.14 V

`E_(cell)=E_(cell)^@ - (0.0591)/n log [Cr^(3+)]^2/[Fe^(2+)]^3`

(Nernst Equation)

`0.261 = E_(cell)^@ = 0.0591/6 log [0.001]^2/[0.001]^3`

`0.261 = E_(cell)^@ - (0.591 xx 2)/6`

`E_(cell)^@ = 0.2807V`

Concept: Electrolytic Cells and Electrolysis - Introduction

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