posted by Nick on .
The Ksp for cerium iodate, Ce(IO3)3 is 3.2 e-10. What is the molar solubility of Ce ion in pure water?
= .0019 M
B) A 0.031 M sodium iodate is added as a common ion. What is the concentration of Ce ion with the common ion present?
C) What is the ratio of the Ce ion with the common ion added to the Ce ion in pure water?
Ce ion with common ion / Ce ion in pure water
how do i go about starting this problem for B and C?
Ksp = (Ce^+3)(IO3^-)^3
For B, enter IO3^- as 0.031 (from NaIO3). Technically, if S is solubility of Ce(IO3)3, then 3S is concn of IO3^- so in the NaIO3 soln, concn is 3S + 0.031; however, in general, 3S is so small in comparison to the common ions that are added that 3S can be neglected. It is good to leave them in, neglect them, solve the problem for Ce^+3, then check the assumption and see if it is valid. In my many years of doing this I have found one (just 1) case in which the 3S could NOT be neglected.
For C, just right the ratio of one over the other and you have it.