Silver chromate is sparingly soluble in aqueous solutions. The 𝐾sp of Ag2CrO4 is 1.12×10−12 .

Question

What is the solubility (in mol/L) of silver chromate in 1.00 M potassium chromate aqueous solution?

Answer 1

The dissociation is Ag₂CrO₄ ==> 2Ag¹⁺ + CrO₄^2-.

K_sp = [Ag¹⁺]² [CrO₄²-]

As the added CrO₄^2- results in the common ion effect and the very slight solubility of Ag₂CrO₄, the molarity of the K₂CrO₄ can be used for [CrO₄^2-].

Therefore, [Ag¹⁺] = √(1.12 x 10^-12 / 1.00) = √1.12 x 10^-12 = 1.06 x 10^-6. Since the number of Ag ions produced is twice that of the Ag₂CrO_4, the concentration of Ag₂CrO₄ is 1/2 (1.06 x 10^-6) = 5.29 x 10^-7 M.

Please check math.