Q. Solid $Ba\left( NO_{3} \right)_{2}$ is gradually dissolved in a $1.0 \times 10^{- 4}$ M $Na_{2}CO_{3}$ solution. At what concentration of $Ba^{2 +}$ will a precipitate begin to form? ($K_{sp}\ for\ {BaCO}_{3} = 5.1 \times 10^{- 9})$

A) $4.1 \times 10^{- 5}$ M
B) $5.1 \times 10^{- 5}$ M
C) $8.1 \times 10^{- 8}$ M
D) $8.1 \times 10^{- 7}$ M
Explanation

(b)
$K_{sp}\left\lbrack BaCO_{3} \right\rbrack = \left\lbrack Ba^{2 +} \right\rbrack\lbrack CO_{3}^{2 -}\rbrack$
$\left\lbrack Ba^{2 +} \right\rbrack = \frac{K_{sp}}{\lbrack CO_{3}^{2 -}\rbrack} = \frac{5.1 \times 10^{- 9}}{1 \times 10^{- 4}}$
$\left\lbrack Ba^{2 +} \right\rbrack = 5.1 \times 10^{- 5}\ M$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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