Chapter 5, Problem 72QAP

Interpretation Introduction

Interpretation:

The acid used in the generation of CO₂ gas from Na₂ CO₃ is to be determined.

Concept introduction:

Na₂ CO₃ reacts with both HCl and H₂ SO₄ to evolve gaseous carbon dioxide, CO₂ . The reactions are outlined below.

$\begin{array}{l}{\text{Na}}_2{\text{CO}}_3\left(s\right)+2\text{ HCl}\left(aq\right)\to \text{2 NaCl}\left(aq\right)+{\text{CO}}_2\left(g\right)+{\text{H}}_2\text{O}\left(l\right)\left(1\right)\\ {\text{Na}}_2{\text{CO}}_3\left(s\right)+{\text{H}}_2{\text{SO}}_4\left(aq\right)\to {\text{Na}}_2{\text{SO}}_4\left(aq\right)+{\text{CO}}_2\left(g\right)+{\text{H}}_2\text{O}\left(l\right)\left(2\right)\end{array}$

As per stoichiometric equation (1),

${\text{2 mol HCl = 1 mol CO}}_2$

As per stoichiometric equation (2),

${\text{1 mol H}}_2{\text{SO}}_4=1{\text{ mol CO}}_2$

By taking a ratio of the number of moles of acid used to the number of moles of CO₂ evolved, the identity of the acid can be established.