Solid BaNO32 is gradually dissolved in a 1.0 × 10-4 M  Na2CO3 solution. At what concentration of Ba2+, will a precipitate begin to form ?KSP for  BaCO3 = 5.1 × 10-9

Na2CO3  ⇌  2Na+ + CO32-Na2CO3  =  CO32- = 1 ×  10-4 MBaCO3 ⇌   Ba2+ + CO32-KSP BaCO3 = Ba2+  CO32-Ba2+    =   KSP BaCO3CO32-  Ba2+    =   5.1 ×  10-91 ×10-4Ba2+    = 5.1 ×  10-5 MHence, at  5.1 × 10-5  concentration of  Ba2+, a precipitate will begin to form.