Question

What is the molar solubility of $Al(OH)_3$ in $0.2\, M\, NaOH$ solution ? Given that, solubility product of $Al(OH)_3 = 2.4 \times 10^{-24}$ :

• A. $ 12 \times 10^{- 23}$
• B. $ 12 \times 10^{- 21 }$
• C. $ 3 \times 10^{- 19}$
• D. $ 3 \times 10^{- 22}$

Answer 1

Answer: (D)

$ Al(OH)_3 \rightleftharpoons Al^{+3} + 3OH^{-} $
$S' \; 0.2 + 3 (S') \simeq 0.2$
$S; \times (0.2)^3 = k_{sp} = 2.4 \times 10^{-24}$
$(S') = 3 \times 10^{-22} M $