Gen Chem Explanation needed!

[wizkidz]

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Can someone explain the answer to this question please? Not quite understanding the concept here...Thank You!

Which 0.1 M cation solution, when added to a 100 mL 0.1M Na2CO3 dropwise, would form a precipitate first?

• A. Mg2+ (Ksp MgCO3 = 1.0 × 10–5)
• B. Ca2+ (Ksp CaCO3 = 5.2 × 10–12)
• C. Hg22+ (Ksp Hg2CO3 = 9.0 × 10–17)
• D. Ba2+ (Ksp BaCO3 = 2.0 × 10–9)
• E. All would form a precipitate at the same rate since all are 2+ ions.

 

[DrHJ]

I think the correct answer is C. The one with the lowest Ksp is the one which is the least soluble. 9.0*10-17 is the smallest Ksp of all.

 

[confusedhopeful]

The answer is B. Solubility is calculated by the molar solubility not ksp.


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