# Question #7c902

Dec 13, 2014

This is a fairly straightforward pH problem, all you need to know is that

$\left[{H}_{3}^{+} O\right] = {10}^{- p H}$

Plugging in the pH value will produce

$\left[{H}_{3}^{+} O\right] = {10}^{- 8.85} = 0.00000000141 = 1.4 \cdot {10}^{- 9} M$

SInce the pH is greater than 7, you are dealing with a basic solution

$p O H = 14 - p H = 14 - 8.85 = 5.15$

This means the concentration of $O {H}^{-}$ is

$\left[O {H}^{-}\right] = {10}^{- p O H} = {10}^{-} 5.51 = 7.1 \cdot {10}^{-} 6 M$