A solution of Na3AsO4 is added dropwise to a solution that is 0.0643 M in Bi3+ and 0.000180 M in Cd2+.
The Ksp of BiAsO4 is 4.43e-10.
The Ksp of Cd3(AsO4)2 is 2.2e-33.
(a) What concentration of AsO43- is necessary to begin precipitation? (Neglect volume changes.)
[AsO43-] = __?__ M.