Question

Select the incorrect statement for pure water at a certain temperature where $K_w$ for water is $4\times 10^{-14}$ .
$log2=0.3$

• A. $pH=6.7$ and water is acidic
• B. $pH=6.7$ and water is neutral
• C. $pOH=6.7$ and water is neutral
• D. $pH+pOH=13.4$

Answer 1

Answer: (A)

$\left[H^{+}\right]\left[O{H}^{-}\right]=K_w=4\times 10^{-14}$
In pure water $\left[H^{+}\right]=\left[O{H}^{-}\right]$
$\therefore \left[H^{+}\right]=2\times 10^{-7}$
or $pH=7-log2=7-0.3=6.7=pOH$
Pure water is neutral