A solution containing a mixture of 0.0379 M potassium chromate (K2CrO4) and 0.0739 M sodium oxalate (Na2C2O4) was titrated with a solution of barium chloride (BaCl2) for the purpose of separating CrO2-4 and C2O2-4 by precipitation with the Ba2 + cation. The solubility product constants (Ksp) for BaCrO4 and BaC2O4 are 2.1010-10 and 1.3010-6, respectively. Which barium salt will precipitate first?

Question

Reilly Carey

Chemistry

8 December, 00:07

A solution containing a mixture of 0.0379 M potassium chromate (K2CrO4) and 0.0739 M sodium oxalate (Na2C2O4) was titrated with a solution of barium chloride (BaCl2) for the purpose of separating CrO2-4 and C2O2-4 by precipitation with the Ba2 + cation. The solubility product constants (Ksp) for BaCrO4 and BaC2O4 are 2.1010-10 and 1.3010-6, respectively. Which barium salt will precipitate first?

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Answers (1)

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Paloma Bass · Answer 1

BaCrO₄ will precipitate first.

Explanation:

For a generic salt (AB) that is soluble in some solvent, the solubility product constant (Kps) is:

AB (s) ⇄ A⁺ + B⁻

Kps = [A⁺]*[B⁻]

So, as greater is Kps, as higher is the solubility, and more difficult will be to form a precipitated (the solid form of the salt).

Kps of BaCrO₄ < Kps of BaC₂O₄, so BaCrO₄ will precipitate first.