Question

The solubility product of silver chloride is 1.0*(10 power -10) at 25°C.calculate the solubility of silver chloride in pure water and 0.2M of sodium chloride solution

Answer 1

The solubility of silver chloride in pure water is equal to 10^-5 M while the solubility of silver chloride in 0.2 M sodium chloride is equal to 5×10^-10 M.

• Let S be the solubility of silver chloride.
• In pure water, [Ag+]=[Cl-]=S
• In 0.2M NaCl , [Ag+]=S and [Cl-]=S+0.2 , sodium chloride being a strong electrolyte dissociates completely into water.
• In pure water , Ksp = S² ⇒ S=√Ksp = 10^-5 M
• In 0.2 M NaCl , Ksp = S(S+0.2) , since (S<<0.2) , (S+0.2≈0.2)  

        So, Ksp = 0.2×S ⇒ s= ksp/0.2 = 5×10^-10 M