Lesson: Net Ionic Equations

Introduction

In chemistry, net ionic equations are used to represent the actual chemical species that are involved in a reaction. They focus on the ions that participate in the reaction while omitting the spectator ions that do not change during the reaction.

Steps to Write Net Ionic Equations

1. Write the balanced molecular equation for the reaction.
2. Split the soluble strong electrolytes (soluble salts, strong acids, and strong bases) into their respective ions (dissociation).
3. Identify and remove spectator ions (ions that appear on both sides of the equation).
4. Write the net ionic equation with only the ions and molecules that undergo a change.

Example: Reaction of Sodium Sulfate and Barium Nitrate

1. Balanced Molecular Equation:
   ${Na}_{2} {SO}_{4} (aq) + {Ba(NO}_{3} {)}_{2} (aq) \rightarrow {BaSO}_{4} (s) + 2 {NaNO}_{3} (aq)$

2. Dissociated Ionic Equation:
   $2{Na}^{+} (aq) + {SO}_{4}^{2-} (aq) + {Ba}^{2+} (aq) + 2 {NO}_{3}^{-} (aq) \rightarrow {BaSO}_{4} (s) + 2 {Na}^{+} (aq) + 2 {NO}_{3}^{-} (aq)$

3. Identify Spectator Ions:
   The ions ${Na}^{+}$ and ${NO}_{3}^{-}$ are spectator ions.

4. Net Ionic Equation:
   ${Ba}^{2+} (aq) + {SO}_{4}^{2-} (aq) \rightarrow {BaSO}_{4} (s)$ This equation shows the formation of barium sulfate, a solid precipitate.

Key Questions

• What are spectator ions, and why are they omitted from net ionic equations?
• How do you identify which compounds are soluble and which are not?
• Why is it important to write net ionic equations for reactions?

Keywords

• Net Ionic Equation
• Spectator Ions
• Soluble Compounds
• Precipitation Reaction
• Dissociation