Definition of pH: $-log[H^+]$
Therefore, $[H^{+}]=10^{-pH}$
DONT USE pOH MS PILLING DOES NOT LIKE pOH
$K_w$: ionic product of water at 25$\degree$c. ($1 \times 10^{-14}$)
IF THEY DON'T GIVE YOU TEMPERATURE ALWAYS ASSUME ITS 25
Use $[H^{+}] = \frac{K_w}{[OH^-]}$
