Chapter 16, Problem 117A

Interpretation Introduction

Interpretation: The net ionic equation of the given reaction, ${\text{Na}}_{\text{2}}\text{S}+2\text{HI}\to 2{\text{NaI+H}}_2\text{S}$ is to be determined.

Concept introduction: The chemical equations that represent ionic compounds as respective ions are referred to as ionic equations. For example, $\text{NaCl}$ involved in a particular reaction is represented as ${\text{Na}}^{+}$ and ${\text{Cl}}^{-}$ in the case of an ionic equation.

Answer to Problem 117A

  ${\text{2Na}}^{+}+{\text{S}}_2{}^{-}+2{\text{H}}^{+}+{\text{I}}^{2-}\to {\text{2Na}}^{+}+{\text{I}}^{2-}+2{\text{H}}^{+}+{\text{S}}_2{}^{-}$

Explanation of Solution

The net ionic equation involves the representation of ions that has direct involvement in a particular chemical reaction. The ions that are present in common in an ionic equation are canceled out upon writing the net ionic equation. For the reaction,

  ${\text{Na}}_{\text{2}}\text{S}+2\text{HI}\to 2{\text{NaI+H}}_2\text{S}$

The ionic equation is,

  ${\text{2Na}}^{+}+{\text{S}}_2{}^{-}+2{\text{H}}^{+}+{\text{I}}^{2-}\to {\text{2Na}}^{+}+{\text{I}}^{2-}+2{\text{H}}^{+}+{\text{S}}_2{}^{-}$

All the ions are present in common on each side.