Some Basic Concepts Of Chemistry Question 59
Question: What is the molarity of $ SO_4^{2-} $ ion in aqueous solution that contain 34.2 ppm of $ Al _2{{(SO _4)}_3} $ ? (Assume complete dissociation and density of solution 1 g/mL)
Options:
A) $ 3\times {10^{-4}}M $
B) $ 2\times {10^{-4}}M $
C) $ {10^{-4}}M $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
[a] $ \frac{massofAl _2{{( SO _4 )}_3}}{massofwater}\times 10^{6}=34.2 $ 1 litre solution contains 1000 g of water
$ \Rightarrow $ In 1 litre solution, mass of $ Al _2{{(SO _4)}_3}=\frac{34.2\times 1000}{10^{6}}=34.2mg $ Molarity of $ Al _2{{(SO _4)}_3}=\frac{34.2\times {10^{-3}}}{342}M={10^{-4}}M $
$ \underset{{10^{,-,4}}M}{\mathop{Al _2{{(SO _4)}_3}}},(aq)\xrightarrow{{}}\underset{2\times {10^{-4}}M,3\times {10^{-4}}M}{\mathop{2A{l^{3+}}(aq)+3SO_4^{2-}(aq)}},][[ SO_4^{2-} ]=3\times {10^{-4}}M]~ $
