Question

Use your experimentally determined value of Ksp (1.13E-10), and show, by calculation that Ag2CrO4 should precipitate when you add 2.0 mL of 0.004M silver nitrate to 4.0 mL of 0.0012 M potassium chromate. Hint: calculate Q.

Answer 1

concentration of AgNO3 = 2.0 x 0.004 / 2.0 + 4.0

                                       = 0.00133 M

concentration of K2CrO4 = 4.0 x 0.0012 / 2.0 + 4.0

                                       = 0.00080 M

Ag2CrO4 -------------> 2 Ag+ +   CrO42-

Q = [Ag+]^2[CrO42-]

= (0.00133)^2(0.00080)

Q = 1.42 x 10^-9

here Q > Ksp .

so Ag2CrO4 should precipitate