Question

Can Anyone Help Me With This Solubility Problem?
An aqueous solution of 1.90 M AgNO3 is slowly added from a buret to an aqueous solution of 0.0100 M Cl- and 0.250 M I-.
b) When the second ion begins to precipitate, what is the remaining concentration of the first ion?

Reposting this because i already know how to do the other ones. for part B, what is the setup i use to solve this? thx

Answer 1

Bob Pursley gave you a hint this morning. Here is another one.
Divide Ksp AgCl/Ksp AgI =
(Ag^+)(Cl^-)/(Ag^+)(I^&-) = (KspAgCl)/(Ksp AgI).
(Ag^+) cancels so you can get a ratio of
(Cl^-)/(I^-) = ??
Substitute numbers and solve for (Cl^-)

Answer 2

the ksp for AGCL is 1.8*10^-11, and the ksp for AGI came out to 8.5*10^-11. when i divided the numbers and set them equal to CL/0.250, the number came out really large? is that right?

Answer 3

Yes, the number is a large one. A couple of words of caution.
1. AGCL and AgCl are two different things. The same goes for AGI versus AgI. You need to use more caps to begin a sentence and fewer caps for symbols.
2. I don't believe either of your values for Ksp and that will affect the ratio you calculated (although, I agree it is a large number).