What is the `pH` of the resulting solution when equal volumes of `0.1 M NaOH` and `0.01 M HCl` are mixed?

Options

A. `12.65`
B. `2.0`
C. `7.0`
D. `1.04`

Answer

A

Explanation

Key Concept - When equal volumes of acid and base are mixed, then resulting solution become alkaline if concentration of base is taken high. Let normality of the solution after mixing 0.1 M NaOH and 0.01 M HCl is N.
`therefore N_(1)V_(1)-N_(2)V_(2)=NV`
or `0.1xx1-0.01xx1=Nxx2`
Since, normality of NaOH is more than that of HCl. Hence, the resulting solution is alkaline.
or `[overset(-)(O)H]=N=(0.09)/(2)=0.045 N`
or `pOH=-log(0.045)=1.35`
`therefore pH=14-pOH=14-1.35=12.65`