Question

What is the concentration of Ag+ remaining in solution?

Calculate the following when 0.250 L of 0.249 M AgNO3 solution is mixed with 0.350 L of 0.300 M Na2CO3 solution.
Ksp for Ag2CO3 is 8.46E-12.

A) What mass of the precipitate forms?
I found out the answer: 8.59 g.
But I don't know how to solve B, I attempted it and got it wrong.

B) What is the concentration of Ag+ remaining in solution?

Answer 1

B.
Let x = solubility of Ag2CO3
Ag2CO3 ==> 2Ag^+ + CO3^2-
...x........2x.......x

Ksp = (Ag^+)^2(CO3^2-)
You know Ksp or can look it up. Calculate how much of the CO3^2- was used in part A and subtract from the initial amount CO3^2- in the problem. Substitute this into Ksp expression for CO3^2- and solve for x = Ag2CO3, then multiply that by 2 to find 2x = (Ag^+).