What Is the Approximate Concentration of Free Fe²⁺ Remaining at Equilibrium

question 27

Multiple Choice

What is the approximate concentration of free Fe²⁺ remaining at equilibrium in a solution prepared by mixing 5.0 mL of 0.10 M FeSO₄ with 5.0 mL of 2.0 M KCN? [The net formation constant for the hexacyanoferrate(II) ion is 1 × 10³⁷.]

• A) 3 × 10^-22 M
• B) 7 × 10^-30 M
• C) 4 × 10^-38 M
• D) 5 × 10^-37 M
• E) 4 × 10^-40 M

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