Equilibrium Question 459
Question: The $ pH $ of the aqueous solution containing $ 0.49gm $ of $ H_2SO_4 $ in one litre is [EAMCET 1997]
Options:
A) 2
B) 1
C) 1.7
D) 0.3
Show Answer
Answer:
Correct Answer: A
Solution:
Moles of $ H_2SO_4=\frac{0.49}{98}=5\times {10^{-3}} $
moles of $ H_2SO_4 $ present per litre of solution (molarity) $ =\frac{.005}{1}=.005 $ M. $ H_2SO_4+2H_2O $ ⇌ $ 2H_3{O^{+}}+SO_4^{-,-} $
one mole of $ H_2SO_4 $ give 2 moles of $ H_3{O^{+}} $ ions. $ H_3{O^{+}}=2\times (H_2SO_4) $
$ =2\times 0.005=0.01 $ M $ [{H^{+}}]={10^{-2}} $ M ; $ pH=2 $
