Answer
$[OH^-] = 0.15M$
$[H_3O^+] = 6.667\times 10^{- 14}M$
pH = 13.18
pOH = 0.82
Work Step by Step
1. Since NaOH is a strong base: $[OH^-] = [NaOH] = 0.15M$
2. Calculate pOH and pH:
$pOH = -log[OH^-]$
$pOH = -log( 0.15)$
$pOH = 0.8239$
$pH + pOH = 14$
$pH + 0.8239 = 14$
$pH = 13.1761$
3. Now, find $[H_3O^+]$
$[OH^-] * [H_3O^+] = Kw = 10^{-14}$
$ 1.5 \times 10^{- 1} * [H_3O^+] = 10^{-14}$
$[H_3O^+] = \frac{10^{-14}}{ 1.5 \times 10^{- 1}}$
$[H_3O^+] = 6.667 \times 10^{- 14}$
