JEE Advanced levelSingle correct optionDifficulty 3 of 3ia210
Solid AgCl (Ksp=1.6×10−10) and solid AgX2CrOX4 (Ksp=1.9×10−12) are both in equilibrium with pure water. Neglecting hydrolysis of CrOX4X2−, the concentration of ClX− in the solution is
A1.56×10−4M
B1.02×10−6M
C1.26×10−5M
D7.77×10−5M
Answer: B
Let a=[AgX+]. Charge balance: a=K1/a+2K2/a2, i.e. a3−1.6×10−10a−3.8×10−12=0, so a=1.56×10−4M. Then [ClX−]=1.6×10−10/a=1.02×10−6M (and [CrOX4X2−]=7.77×10−5M).