Chapter 15, Problem 35QAP

A solution is made up by adding 0.632 g of barium nitrate and 0.920 g of lanthanum nitrate, to La(NO₃)₃ enough water to make 0.500 L of solution. Solid sodium iodate, NalO₃, is added (without volume change) to the solution.

(a) Which salt will precipitate first? La(IO₃)₃ $\left(K_{\text{sp}}=7.50\times {10}^{-12}\right)$ or BAIO₃ $\left(K_{\text{sp}}=4.0\times {10}^{-9}\right)$?

(b) What is [IO₃^-] when the salt in (a) first begins to precipitate?