Chapter 19.4, Problem 35SP

Interpretation Introduction

Interpretation : The moles of potassium hydroxide needed to neutralize $1.56\text{mol}$ of phosphoric acid is to be calculated.

Concept Introduction : Salt and water are created when bases and acids react.

A strong acid and strong base react completely to form a neutral solution. A neutralization reaction is a name for this kind of reaction.

Answer to Problem 35SP

The moles of potassium hydroxide needed to neutralize $1.56\text{mol}$ of phosphoric acid is $4.68\text{mol}$ .

Explanation of Solution

The aqueous solution of $1.56\text{mol}$ of phosphoric acid is given.

The reaction between potassium hydroxide and phosphoric acid is given as

  ${\text{H}}_{\text{3}}{\text{PO}}_{\text{4}}\left(aq\right)\text{+}3\text{KOH}\left(aq\right)\to {\text{K}}_3{\text{PO}}_4\left(aq\right)\text{+}3{\text{H}}_{\text{2}}\text{O}\left(l\right)$

The above reaction is balanced.

The mole ratio is $1:3$ for the reaction between ${\text{H}}_{\text{3}}{\text{PO}}_{\text{4}}$ and $\text{KOH}$ .

The moles of potassium hydroxide are calculated as follows:

  $\begin{array}{c}\text{Moles of KOH}\text{=}\frac{3\text{mol KOH}}{1\cancel{{\text{mol H}}_3{\text{PO}}_4}}\times 1.56\cancel{\text{mol}{\text{H}}_3{\text{PO}}_4}\\ =4.68\text{mol}\text{KOH}\end{array}$