Question

Which of the following solutions will have $pH=10$ at $298K$?

• A. $1\times {10}^{-9}MHCl$ solution
• B. $1\times {10}^{-4}MNaOH$ solution
• C. $1\times {10}^{-9}MKOH$ solution
• D. Both $\left(a\right)$ and $\left(b\right)$

Answer 1

The correct option is B $1\times {10}^{-4}MNaOH$ solution

$pH=-log\left[H^{+}\right]$

$1\times {10}^{-4}MNaOH,$

$pOH=-log\left[O{H}^{-}\right]=4$

So $pH=14-4=10$.

${10}^{-10}M$ HCl solution will have pH less than 7 due to contribution of hydrogen ion from water.

$\left[H^{+}\right]={10}^{-10}+{10}^{-7}$

pH $=-log\left[H^{+}\right]=6.98$