Question
Chemistry Question on Acids and Bases
The pH of a 10−8 molar solution of HCl in water is
A
8
B
between 7 and 8
C
between 6 and 7
D
None of these
Answer
between 6 and 7
Explanation
Solution
pH=−log[H+]=−log10−8=8
It is not possible for acid, so it is [H+], the [H+] of water is also added. Total [H+] in solution
=[H+] of HCl+[H+] of water
=(1×10−8+1×10−7)M
=(1+10)×10−8=11×10−8M
∴pH=−log[H+]
=−log11×10−8
=−log11+8log10
=−1.0414+8=6.9586