Question 3.EP.4: When aqueous sodium carbonate is added to barium chloride, t...
When aqueous sodium carbonate is added to barium chloride, the solution turns cloudy white with solid barium carbonate. Write the molecular, ionic, and net ionic equations for this reaction.
Strategy
First we will use the nomenclature rules that we presented in Chapter 2 to write formulas for all of the compounds involved. Then we construct a balanced chemical equation using complete formula units. Next we must identify any ionic compounds that are present, and we write them as dissociated ions to give the total ionic equation. Finally, to obtain the net ionic equation, we must eliminate any spectator ions from both sides of the equation.
Formulas for the substances listed are Na_{2}CO_{3}, BaCl_{2}, and \ BaCO_{3}. Although BaCO_{3} is the only product listed in the problem statement, the sodium and chlorine atoms must also appear somewhere on the right-hand side of our equation. So NaCl will also be produced as a product. We write reactants on the left and products on the right to set up the molecular equation:
Na_{2}CO_{3}(aq)+BaCl_{2}(aq)\longrightarrow BaCO_{3}(s)+2NaCl(aq)
Next we recognize that the three substances denoted as “(aq)” in that equation will exist as dissociated ions rather than intact molecules. This leads us to the total ionic equation:
2 \ Na^{+}(aq)+CO_{3} \ ^{2-}(aq)+Ba^{2+}(aq)+2 \ Cl^{-}(aq)\longrightarrow BaCO_{3}(s)+2 \ Na^{+}(aq)+2 \ Cl^{-}(aq)Finally, we can cancel the sodium and chloride ions because they appear in equal numbers on both sides of the equation. This leads us to the net ionic equation:
CO_{3} \ ^{2-}(aq)+Ba^{2+}(aq)\longrightarrow BaCO_{3}(s)
