Question

What is the minimum concentraition of $SO_{4}^{2 -}$required to precipitate $BF_{3}$in a solution containing $AlCl_{3}$ mole of $FeCl_{3}$ ($PH_{3}$ of $SO_{4}^{2 -}$)

• A. $HSO_{4}^{-}$
• B. $H^{+}$
• C. $H_{2}SO_{4}$
• D. $SO_{4}^{2 -}$

Answer 1

Answer: (C)

$H_{2}SO_{4}$

Answer 2

$\underset{Conc.:}{BaSO_{4}}$ $\underset{1 \times 10^{- 4}}{Ba^{2 +}} + \underset{s}{SO_{4}^{2 -}}$

$K_{sp} = 4 \times 10^{- 10}$

$4 \times 10^{- 10} = 1 \times 10^{- 4} \times s$

$s = \frac{4 \times 10^{- 10}}{1 \times 10^{- 4}} = 4 \times 10^{- 6}M$