Solubility of Salt in Different pH conditions

Hi AWK,

Thanks for the comment. I was referring to the hydrolysis of the salt instead of the buffer.

CH3COONa (s) <---> CH3COO- (aq) + Na+(aq)    (equilibrium)
CH3COO- + H2O <---> CH3COOH + OH-  (equilibrium)

If it is in accordance what was stated, the equilibrium of the second equation shifts the right as pH of the media is lower and [AcO-] decreases. As a result, the equilibrium for the first reaction is shifted to the right hence increasing its solubility?

Similar for the aniline hydrochloride,

ArNH2.HCl (s) <---> ArNH3+ (aq) + Cl- (aq)  (equilibrium)
ArNH3+ + H2O <---> ArNH2 + H3O+ (equilibrium)

as the pH of the media decreases, the equilibrium for the second reaction is shifted towards the left and thus producing more [ArNH3+]. As more [ArNH3+] is formed, the equilibrium for the first equation is shifted left and hence reducing its solubility?

You're missing the point. If the second equilibrium is shifted to the right, [AcO^-] is reduced and the first equilibrium is shifted to the right.

If you change pH of hydrolysing salt, the problem changes to a buffer solution.

You are right, it is true that acetic acid is miscible with water even when it's uncharged. Hence, would you say that the solubility of sodium acetate is unaffected by the pH of the media? How about in the case for aniline hydrochloride?

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The equilibrium for the second equation will be shifted to the right and hence forming more acetic acid (uncharged) and decreasing the solubility of the salt.

Why would that decrease the solubility of the salt?

Your problems concern hydrolysis of salts or buffer solutions.