Chapter 14.4, Problem 14.8P

Interpretation Introduction

Interpretation:

Concentration of ${\text{OH}}^{\text{-}}$ has to be calculated and the solution has to be classified as acidic, basic or neutral.

Concept introduction:

Ion-product constant value$\left(K_w\right)$:

At $\text{25°C}$ we can calculate the numerical value of ${\text{K}}_{\text{w}}$:

$\begin{array}{l}{\text{K}}_{\text{w}}\text{=}\left[{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}\right]\left[{\text{OH}}^{\text{-}}\right]\\ =\left(1.0\times {10}^{-7}\right)\left(1.0\times {10}^{-7}\right)\\ =1.0\times {10}^{-14}\end{array}$

We can differentiate acidic, basic and neutral solution based on the relative values of concentration of ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ion and ${\text{OH}}^{\text{-}}$ ion.

Acidic:$\left[{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}\right]>\left[{\text{OH}}^{\text{-}}\right]$

Basic: $\left[{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}\right]<\left[{\text{OH}}^{\text{-}}\right]$

Neutral: $\left[{\text{H}}_{\text{3}}{\text{O}}^{\text{+}}\right]=\left[{\text{OH}}^{\text{-}}\right]$