A solution contains 0.001M Cu+ and 0.020M Pb2+. Suppose that solid KI is added until a precipitate just forms. What is [I-] when this first occurs? PbI2 (K = 1.4E-8) CuI (K = 5.3E-12)

Now describe what happens if enough KI has been added to reduce [Cu+] to 1E-9M.

a. [I-] = 5.3E-9; so as consequence, [Pb2+] = 2.6E-6 and both ions have precipitated

b. [Pb2+] = 5.0E-4 and so both ions will have precipitated

c. Right after the addition QPbI2 = 5.6E-7 > 1.4E-8 so Pb2+ will precipitate

d. Right after the addition QPbI2 < 1.4E-8 so no lead ion precipitates

e. 1 and 3

f. 2 and 3