A solution in equilibrium with solid barium phosphate (ba3(p o4)2) is found to have a barium ion concentration of 0.0005 m and a ksp of 3.4 x 10−23. calculate the concentration of phosphate ion. 1. 2.6x10−7 2. 1.04x10−6 3. 5.2x10−7 4. 1.3x10−7 5. 2.7x10−13