Question

Select the incorrect statement for pure water at a certain temperature where $K_{w}$ for water is $4 \, \times \, 10^{- 14}$ .
$log 2 \, =0.3$

• 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 $pH=7 \, - \, log 2=7 \, - \, 0.3=6.7=pOH$
Pure water is neutral