Aqueous solutions of Zn+2 and Pb+2 both .0010M. Both form insoluble sulfides. Appx. what pH will allow maximum precipitation of one ion and leave the other in solution?
Do I just use Ksp and the equations? If so what do I do next?
See the selective solubility notes and example here:
http://pages.towson.edu/ladon/solprod.html
Set up Ksp for Zn(OH)2 and Pb(OH)2.
Calculate (OH^-) for each using 0.001 M for the metal. From this you will see which metal requires the least OH^- and that will tell you the approximatre pH needed. To check yourself, put the (OH^-) back into the Ksp and calculate how much of the metal ion can be in solution.
Post your work if you want us to review it.