Question

Calculate the $pH$ of the resulting solution formed by mixing the following solutions.
$20mL$ of $0.2MBa(OH{)}_2$ + $30mL$ of $0.1MHCl$

Answer 1

$m$ moles of $O{H}^{-}=20\times 0.2\times 2=8$

$m$ moles of $H^{+}=30\times 0.1\times 1=3$

$\therefore$ $m$ moles of $O{H}^{-}$ left= $8-3=5$

$\Rightarrow \left[O{H}^{-}\right]=\frac{5}{20+30}=0.1M$

$\therefore pOH=-\log 0.1=1$

$\therefore pH=14-pOH=13$