Answer
$[H^+] = 1.41 \times 10^{-3}$
$[OH^-] = 7.08 \times 10^{-12}$
Work Step by Step
Equations that will be used:
$[H^+] = 10^{-pH}$
$[OH^-] = 10^{-pOH}$
$pH + pOH = 14$
1. Calculate the $[H^+]$
$[H^+] = 10^{-2.85} = 1.41 \times 10^{-3}$
2. Find the pOH
$2.85 + pOH = 14$
$pOH = 14 - 2.85 = 11.15$
3. Calculate $[OH^-]$
$[OH^-] = 10^{-11.15} = 7.08 \times 10^{-12}$