Question

State True or False.

Ionic product of water changes by the addition of acid or base.

• A. True
• B. False

Answer 1

The correct option is B False

Consider the following reaction:

$K_w$ is the equilibrium constant of the following reaction:
$2H_{2}O$ $\leftrightarrow$ $H_3{O}^{+}+O{H}^{-}$

$K_w$ $=$ ${10}^{14}$ at ${25}^{o}C$ . At this temperature, $\left[H_3{O}^{+}\right]=[O{H}^{]}$ $={10}^7$ mol/L. If you add acid to water, the above reaction equilibrium is displaced in order to counteract the change in the concentration of ion hydronium, i.e. the reaction is displaced to the left. This means that ions hydroxide will react with the excess of ions hydronium to give water. As a result: the concentration of ion hydroxide will be less than ${10}^7$ mol/L, and the concentration of ion hydronium will be more than ${10}^7$ mol/L. But their product is constant. $\left[H_3{O}^{+}\right]\left[O{H}^{-}\right]$ $={10}^{14}$ .