Salts of strong acids and weak bases

$\mathrm{CuSO_4}$ is salt of strong acid $\mathrm{H_2SO_4}$ and weak base $\mathrm{Cu(OH)_2}$. When $\mathrm{CuSO_4}$ is dissolved in water, it dissociates completely as,

$\mathrm{SO_4^{2-}}$ ions of salt have no tendency to react with water because the possible product $\mathrm{H_2SO_4}$ is strong electrolyte. The reaction of $\mathrm{Cu^{2+}}$ ions with $\mathrm{OH^{-}}$ ions forms unionized $\mathrm{Cu(OH)_2}$. The hydrolytic equilibrium for $\mathrm{CuSO_4}$ is then written as,

Due to the presence of excess of $\mathrm{H_3O^{+}}$ ions, the resulting solution of $\mathrm{CuSO_4}$ becomes acidic and turns blue litmus red. …