A solution of Na2CO3 is added dropwise to a solution that contains 1.34×10−2M Fe^2+ and 1.33×10−2M Cd^2+ . What CO3^2- concentration of is need to initiate precipitation? Neglect any volume changes during the addition.

Question

A solution of Na2CO3 is added dropwise to a solution that contains 1.34×10−2M Fe^2+ and 1.33×10−2M Cd^2+  . What CO3^2- concentration of  is need to initiate precipitation? Neglect any volume changes during the addition.

DrBob222 · Answer

Look up Ksp for FeCO3.
Look up Ksp for CdCO3.
Write Ksp expression for FeCO3.
Write Ksp expression for CdCO3.
Solve FeCO3 expression for CO3^-2 using iron(II) given.
Solve CdCO3 expression for CO3^-2 using Cd^+2 given.
The smallest concn calculated will be the minimum concn of CO3^-2 needed to start pptn. Check my work.