Question

What is the $pH$ of the resulting solution when equal volumes of $0.1\text{M}NaOH$ and $0.01\text{M}HCl$ are mixed?

• A. $7.0$
• B. $1.04$
• C. $12.65$
• D. $2.0$

Answer 1

The correct option is C $12.65$

$N_1{V}_1-N_2{V}_2=$ equivalents of unreacted hydroxyl ions.

$0.1\times 1-0.01\times 1=\left[O{H}^{-}\right]$
$\left[O{H}^{-}\right]=N_R=\frac{0.09}{2}=0.045\text{N}$

$pOH=-\log \left(0.045\right)=1.35$

$\therefore pH=14-pOH=14-1.35=12.65$