Question

Determine the [OH−] , pH, and pOH of a solution with a [H+] of 4.0×10−11 M at 25 °C.

Answer 1

K_w = [H⁺][OH^-] = 1*10^-14

$pH = -lg[H^+]=-log_{10}(4*10^{-11})=10.4$

$pOH = 14-pH = 3.6$

$[OH^-]=10^{-pOH}=0.00025=2.5*10^{-4}$