Question

At a certain temperature for a aqueous solution, the value of $p{K}_w$ is 13.4 and the measured pH of the solution is 7. What is the nature of the solution?

• A. Acidic
• B. Basic
• C. Neutral
• D. Unpredictable

Answer 1

The correct option is B Basic

Since, for a neutral solution $\left[H^{+}\right]=\left[O{H}^{-}\right]$
and $k_w=\left[H^{+}\right]\left[O{H}^{-}\right]$
From the definition of $pH$ and $p{K}_w$ the relation between the two is :
$pH=\frac{1}{2}p{K}_w$
At this temperature , $pH$ of neutral solution would be $=\frac{13.4}{2}=6.7$
$\because 6.7$ is the neutral $pH$ for this solution. So, $pH$ greater than 6.7 at this temperature should be the basic solution.
As, the measured $pH$ of the solution is 7 which is greater than 6.7 , So the given solution is basic in nature.