Question

What is the $pH$ of a $10^{-4}MO{H}^{-}$ solution at $330K$, if $K_w$ at $330K$ is $10^{-13.6}$?

• A. $4$
• B. $9.0$
• C. $10$
• D. $9.6$

Answer 1

Answer: (D)

Given at $330K$
$K_w=10^{-13.6}$
i.e. $P{K}_w=pH+pOH$
$\because pOH=-log\left[O{H}^{-}\right]$
$13.6=pH+pOH$
$pOH=-log10^{-4}$
$13.6=pH+4$
$\therefore pH=13.6-4$
$=9.6$