Question

The solubility of AgCl will be minimum in

• A. $0.001\, M\, AgNO_3$
• B. $pure\, water$
• C. $0.01\, M\, CaCl_2$
• D. 0.01 M NaCl

Answer 1

Answer: (C)

$0.01\, M\, CaCl_2$

Answer 2

The solubility of insoluble substances can be decreased by the presence of a common ion. Present in silver chloride are silver ions ($Ag^+$ ) and chloride ions ($Cl^-)$. $AgCl$ is not soluble in water. Silver nitrate (which is soluble) has silver ion in common with silver chloride. But the concentration of the common ion is low (0.001M) Calcium chloride (also soluble) has chloride ion in common with silver chloride. In $CaCl_2$ has two moles of common ion $(0.02\,M)$ that decreases solubility very rapidly. In $Na_2$ $SO_4$ there is no common ion effect apply therefore is soluble in it.