Equilibrium Question 398
Question: A solution has $ pH=5 $ , it is diluted 100 times, then it will become [NCERT 1978; AFMC 2005]
Options:
A) Neutral
B) Basic
C) Unaffected
D) More acidic
Show Answer
Answer:
Correct Answer: A
Solution:
$ pH=5, $ means $ [{H^{+}}]={10^{-5}}M. $ After dilution $ [{H^{+}}]={10^{-5}}/100={10^{-7}}M $
$ [{H^{+}}] $ from $ H_2O $ cannot be neglected. Total $ [{H^{+}}]={10^{-7}}+{10^{-7}}=2\times {10^{-7}} $
$ pH=7-0.3010=6.6990=7 $ (neutral).
