Question

Given that the solubility product for la(io3)3 is 1.0 x 10-11, what is the concentration of la3+ in a saturated solution of lanthanum iodate answer

Answer 1

$La(IO_3)_3 -----\ \textgreater \ La^{3+} + 3 IO_3^-$

In a saturated solution,
conc. of La3+  =  x  (say)
so, conc. of IO3-  =  3x

Applying solubility product formula:

$10^{-11} = x (3x)^3 = 27x^4$ 

so, 
La^3+ = x = 7.8 * 10^{-4} M