Sketch the Predominance (Pourbaix) diagrams in acidic and basic conditions for cobalt given the following Lattimer diagrams.
Acidic solution: Co3+ +1.808 -> Co2+ -0.277 -> Co
Basic solution: Co(OH)3 - +0.17 -> Co(OH)2 - -0.73 -> Co
Pourbiax diagram is kind of phase diagram, it provides the information about stability of metal as function of pH and potential. These are generally used in corrosion studies. Its also known as potential/pH diagram, equilibrium diagram, pE/pH diagram. In pourbiax diagram, horizontal lines represent electron transfer reaction(they are pH independent but potential dependent) and vertical lines are pH dependent but potential independent and not accompany any electron transfer.
Sloping, straight lines all give information about redox potential in equilibrium. Pourbiax diagram gives information about the stability of metal, corrosion or sctive state, forming passive layers inhibiting the corrosion and thermodyanamic stability.
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