Equilibrium Question 539
Question: Assuming complete dissociation, which of the following aqueous solutions will have the same $ pH $ value [Roorkee Qualifying 1998]
Options:
A) $ NH_3 $ of $ 0.01MHCl $
B) $ _{10}\frac{1}{K _{a}} $ of $ 0.01MH_2SO_4 $
C) $ 50ml $ of $ _{10}\frac{1}{K _{a}} $
D) Mixture of 50 $ ml $ of $ 0.02MH_2SO_4 $ and $ 50ml $ of $ 0.02MNaOH $
Show Answer
Answer:
Correct Answer: A
Solution:
M.eq. of 0.01 $ MHCl=\frac{.01\times 100}{1000}=1\times {10^{-3}} $
$ pH=3 $
M.eq. of .02 $ MH_2SO_4=\frac{.04\times 50}{1000}=2\times {10^{-3}} $
M.eq. of .02 $ MNaOH=\frac{0.02\times 50}{1000}=1\times {10^{-3}} $ Left $ [{H^{+}}]=2\times {10^{-3}}-1\times {10^{-3}}=1\times {10^{-3}} $ ; $ pH=3 $
