Item 2 Part A The solubility-product constants, Ksp, at 25 C for two compounds [

Question

Item 2 Part A The solubility-product constants, Ksp, at 25 C for two compounds [iron(Il) carbonate, FeCO3, and cadmium(II) carbonate, CdCO3] are given by the table A solution of Na2 CO3 is added dropwise to a solution that contains 1.04x10-2 M Fe2+ and 1.48 102 M Cd2+. What concentration of CO3 2 isneed to initiate precipitation? Neglect any volume changes during the addition. Express your answer with the appropriate units. Substance FeC03 2.10×10-11 CdC03 1.80×10-14 Hints CO1.22x10-12 M Submit My Answers Give Up Correct Part B In the solution from Part begins to precipitate? A, what will the concentration of CO be at the moment before Fe Express your answer with the appropriate units

Explanation / Answer

Solution-

CdCO3(s) <=> Cd2+(aq) + CO32-(aq)

Ksp = [Cd2+][CO32-] = 1.80 x 10^-14

[Cd2+] = 1.48 × 10^-2 M

=>1.48 × 10^-2 x [CO32-] = 1.80 x 10^-14

=>[CO32-] = 1.22 x 10-12 M
Now,
FeCO3(s) <=> Fe2+(aq) + CO32-(aq)

Ksp = [Fe2+][CO32-] = 2.10 x 10-11

[Fe2+] = 1.04 × 10-2 M

1.04 × 10^-2 x [CO32-] = 2.10 x 10^-11

[CO32-] = 2.01 x 10-9 M

when ionic product Qsp >= Ksp then precipitation occurs

So [CO32-] = 1.22 x 10-12 M is needed to initiate precipitation and Cd2+ precipitates out first.

When second cation Fe2+ starts to precipitate, [CO32-] = 2.01 x 10-9 M.

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