Use of Pourbaix Diagrams to Predict Corrosion

The following examples are with reference to the Pourbaix diagram for the lead/water system (Fig. 2.18) (Ref 9). 

Example 1 a. Use the Nemst half-cell equation for the hydrogen reaction at PHj = 1 atm and the Pb = Pb2+ + 2e reaction at apb2+ = 10 6 to confirm the value of the pH at which line a intersects line 16 (-6). 

The point of intersection of line 16 (-6) and line a corresponds to the equilibrium of lead at apb2+ = ICh6 with the hydrogen reaction. Since the intersection point represents equilibrium, imagine the following cell and set Ecell = 0. 

K Passivation by oxide or hydroxide layer V//////7A Passivation by hydroxide layer I 1 Immunity 

Example 1 b. Use the Pourbaix diagram to estimate Ecen for the proposed corrosion of lead in deaerated solution at pH = 1 and 

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