Chemistry percipitate question

[n.a.s.h]

Homework Statement

A solution is 1.5×10−2 M in both CrO4^2-and SO4^2-. To this solution, 0.55 M Pb (NO3)2(aq) is slowly added.

Which anion will precipitate first from solution?

a) CrO4^{2-}
b) SO4^{2-}

What is Pb^{2+} concentration at the point at which the second anion begins to precipitate?

Homework Equations

The Attempt at a Solution

k the thing that is confusing me is that the concentration of 0.55 M Pb (NO3)2(aq) was stated. Why is this relevant? because of that i do not know what to do

 

[chemisttree]

Things will begin to ppt when the solubility product is reached. You know the value for the solubility product of both lead sulfate and chromate, you know the initial concentrations of the anions, you need to calculate the concentration of lead at each point in the titration. Don't forget to adjust the concentrations of the anions as you add volume from the lead nitrate solution.