Question

$50 \, mL$ of $H_2O$ is added to $50 \, mL$ of $1 \times 10^{-3}\, M$ barium hydroxide solution. What is the pH of the resulting solution?

• A. 3
• B. 3.3
• C. 11
• D. 11.7

Answer 1

Answer: (C)

11

Answer 2

In water, barium hydroxide is hydrolysed as follows,
$Ba ( OH )_{2} \rightleftharpoons Ba ^{2+}+2 OH ^{-}$
cone, of $Ba ^{2+}=1 \times 10^{-3} M$
cone. Of $\left[ OH ^{-}\right]=2 \times 1 \times 10^{-3} M$
$=2 \times 10^{-3} M$
$pOH =-\log [ OH^ -]$
$=-\log \left(2 \times 10^{-3}\right)$
$=2.69$
$p H+p O H=14$
$p H=14-p O H$
$=14-2.69$
$=11.3$
$=11.0$