Question

Solid Ba(NO3)2 is gradually dissolved in a 1.0×10−4MNa2CO3 solution. At which concentration of Ba2+, precipitate of BaCO3 begins to form?(Ksp for BaCO3=5.1×10−9)

• A. (A) 5.1×10−5M
• B. (B) 7.1×10−5M
• C. (C) 4.1×10−5M
• D. (D) 8.1×10−7M

Answer 1

Answer: (A)

(A) 5.1×10−5M

Answer 2

Explanation:
Given that: Concentration of Na2CO3=1.0×10−4M∴[CO3−]=1.0×10−4Mi.e., s=1.0×10−4MAt equilibrium:[Ba++][CO3−−]=Ksp of BaCO3[Ba++]=Ksp[CO3−−]=5.1×10−91.0×10−4=5.1×10−5MHence, the correct option is (A).