Question

$K_w$ of $H_{2}O$ at 373 K is $1\times {10}^{-12}$. Identify which of the following is not correct.

• A. $p{K}_w$ of $H_{2}O$ is $12$
• B. $pH$ of $H_{2}O$ is $6$
• C. $H_{2}O$ is neutral
• D. $H_{2}O$ is acidic

Answer 1

The correct option is D $H_{2}O$ is acidic

1. $p{K}_{w}of{H}_{2}O=-logp{K}_w=-log{10}^{-12}=12$

2. $K_w=\left[H^{+}\right]\left[O{H}^{-}\right]=[H^{+}{]}^2$

$\Rightarrow \left[H^{+}\right]=\sqrt{{10}^{-12}}={10}^{-6}$

$\Rightarrow pH=-log{10}^{-6}=6$

3. $H_{2}O$ is neutral as $\left[H^{+}\right]=\left[O{H}^{-}\right]$

4. As water is neutral in nature , option 4 is incorrect.