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How do I solve this problem on the concentration of fluorine

If a constant  [F-] is maintained in a solution in which the initial  [Ca2+ ] =0.038M, what percentage of Ca 2+ will remain in solution after the CaF2 precipitate. What [F-] should be maintained to ensure that only 3.4% of the Ca 2+ remains unprecipitated?

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J.R. S. | Ph.D. in Biochemistry--University Professor--Chemistry TutorPh.D. in Biochemistry--University Profes...
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CaF2(s) <==> Ca2+(aq) + 2F-(aq)
Ksp = [Ca2+][F-]2
Look up the Ksp and use it and 0.038 for [Ca2+] and solve for [F-].  Use that to determine moles CaF2 precipitated since 2 moles F- = 1 moles CaF2.  Then determine %Ca2+ remaining in solution.