Answer
$[H_3O^+] = 3.162 \times 10^{- 11}M$
$[OH^-] = 3.162 \times 10^{- 4}M$
This solution is basic.
Work Step by Step
$[H_3O^+] = 10^{-pH}$
$[H_3O^+] = 10^{- 10.5}$
$[H_3O^+] = 3.162 \times 10^{- 11}M$
$[H_3O^+] * [OH^-] = Kw = 10^{-14}$
$ 3.162 \times 10^{- 11} * [OH^-] = 10^{-14}$
$[OH^-] = \frac{10^{-14}}{ 3.162 \times 10^{- 11}}$
$[OH^-] = 3.162 \times 10^{- 4}M$
$[OH^-] > [H_3O^+]$ : Basic solution.
Assuming $25 ^{\circ} C$: pH > 7: Basic solution.
