Question

How does pH value influence the solubility of Pb(NO3)2?

Answer 1

Lead(II) nitrate is an inorganic compound with the chemical formula Pb(NO₃​)₂.  It is soluble in water under low to moderate pH values. At high pH values Pb2+ of Lead(II) nitrate reacts with OH- to form insoluble Pb(OH)_{2 .} Thus the solubility decreases with the formation of Lead II hydroxides on increasing the pH.

Pb2+ (aq) + 2OH- (aq)---> Pb(OH)₂ (s)

For Pb2+ under basic conditions, the poorly soluble, Pb(OH)2 predominates which is a white precipitate. On adding more hydroxide to the solution, [Pb(OH)₄]2- is formed which is again soluble. Adding more hydroxide ions will redissolve the [Pb(OH)2] precipitate as [Pb(OH)4]2-

Pb(OH)2 (s) + 2OH- (aq) ---> [Pb(OH)₄]2- (aq)

The solubility at extremely high pH increases due to the formation of soluble [Pb(OH)₄]^2-

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