Chemistry - Ionic Equilibrium Question with Solution | TestHub

$40\text{m}\text{L}\mathrm{\text{o}}\mathrm{\text{f}}0.1\text{M}\text{H}\text{C}\text{l}=\frac{0.1}{1000}\times 40$

$=0.004\text{m}\text{o}\text{l}\text{e}$

$10\text{m}\text{L}\mathrm{\text{o}}\mathrm{\text{f}}0.45\text{M}\text{N}\text{a}\text{O}\text{H}=\frac{0.45}{1000}\times 10=0.0045\text{m}\text{o}\text{l}\text{e}$

$\therefore \text{N}\text{a}\text{O}\text{H}$left unused$=0.0005\text{m}\text{o}\text{l}\text{e}$

Volume of solution$=50\text{m}\text{L}$

$\therefore \text{M}\text{o}\text{l}\text{a}\text{r}\text{i}\text{t}\text{y}\text{o}\text{f}\text{N}\text{a}\text{O}\text{H}=\frac{0.0005}{50}\times 1000$

$=0.01\text{M}$

Or$\left[\text{O}{\text{H}}^{-}\right]={10}^{-2}\text{o}\text{r}\left[{\text{H}}^{+}\right]={10}^{-12}\text{p}\text{H}=12$