Question

Balance the following equations and write the corresponding ionic and net ionic equations (if appropriate): (a) \(\mathrm{CH}_{3} \mathrm{COOH}(a q)+\mathrm{KOH}(a q) \longrightarrow\) (b) \(\mathrm{H}_{2} \mathrm{CO}_{3}(a q)+\mathrm{NaOH}(a q) \longrightarrow\) (c) \(\mathrm{HNO}_{3}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \longrightarrow\)

Short answer

Balanced equations: \(a) \( \mathrm{CH}_{3} \mathrm{COOH}(a q)+\mathrm{KOH}(a q) \rightarrow \mathrm{CH}_{3} \mathrm{COOK}(a q)+\mathrm{H}_{2}\mathrm{O}(l) \) \ (b) \( \mathrm{H}_{2} \mathrm{CO}_{3}(a q)+2\mathrm{NaOH}(a q) \rightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \) \(c) \( 2\mathrm{HNO}_{3}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \rightarrow \mathrm{Ba}(\mathrm{NO}_{3})_{2}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \) \Ionic equations: suppression due to being similar to the net ionic equations but with spectator ions. \Net Ionic equations: \(a) \( \mathrm{H}^{+}(a q) + \mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2}\mathrm{O}(l) \) \(b) \( 2\mathrm{H}^{+}(a q) + 2\mathrm{OH}^{-}(a q) \rightarrow 2\mathrm{H}_{2}\mathrm{O}(l) \) \(c) \( 2\mathrm{H}^{+}(a q) + 2\mathrm{OH}^{-}(a q) \rightarrow 2\mathrm{H}_{2}\mathrm{O}(l) \)

Step-by-step solution

Balancing equations

First, we balance the reactants and products for each chemical reaction, which simplifies to: \(a) \( \mathrm{CH}_{3} \mathrm{COOH}(a q)+\mathrm{KOH}(a q) \longrightarrow \mathrm{CH}_{3} \mathrm{COOK}(a q)+\mathrm{H}_{2}\mathrm{O}(l) \) \ (b) \( \mathrm{H}_{2} \mathrm{CO}_{3}(a q)+2\mathrm{NaOH}(a q) \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \) \(c) \( 2\mathrm{HNO}_{3}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \longrightarrow \mathrm{Ba}(\mathrm{NO}_{3})_{2}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \)

Writing ionic equations

We show the ions of every compound that is dissolved in water: \(a) \( \mathrm{CH}_{3} \mathrm{COO}^{-}(a q)+\mathrm{H}^{+}(a q)+\mathrm{K}^{+}(a q)+ \mathrm{OH}^{-}(a q) \longrightarrow \mathrm{CH}_{3} \mathrm{COO}^{-}(a q)+\mathrm{K}^{+}(a q)+\mathrm{H}_{2}\mathrm{O}(l) \) \(b) \( 2\mathrm{H}^{+}(a q)+\mathrm{CO}_{3}^{2-}(a q)+2\mathrm{Na}^{+}(a q)+2\mathrm{OH}^{-}(a q) \longrightarrow 2\mathrm{Na}^{+}(a q)+\mathrm{CO}_{3}^{2-}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \) \(c) \( 2\mathrm{H}^{+}(a q)+2\mathrm{NO}_{3}^{-}(a q)+\mathrm{Ba}^{2+}(a q)+2\mathrm{OH}^{-}(a q) \longrightarrow \mathrm{Ba}^{2+}(a q)+2\mathrm{NO}_{3}^{-}(a q)+2\mathrm{H}_{2}\mathrm{O}(l) \)

Writing net ionic equations

We discard ions that are reactive as well as present on both sides of the equation (spectator ions): \(a) \( \mathrm{H}^{+}(a q) + \mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2}\mathrm{O}(l) \) \(b) \( 2\mathrm{H}^{+}(a q) + 2\mathrm{OH}^{-}(a q) \rightarrow 2\mathrm{H}_{2}\mathrm{O}(l) \) \(c) \( 2\mathrm{H}^{+}(a q) + 2\mathrm{OH}^{-}(a q) \rightarrow 2\mathrm{H}_{2}\mathrm{O}(l) \)

Key concepts

Ionic Equations

In chemistry, an ionic equation provides a way to focus on the actual chemical processes occurring in a reaction. Unlike molecular equations, ionic equations make it easier to see how substances interact in aqueous solutions. Ionic equations show all of the ions separately if they are soluble. This means compounds that dissolve in water are broken down into their ions.
For our examples:

• When \( \text{CH}_3\text{COOH}(aq) + \text{KOH}(aq) \rightarrow \text{CH}_3\text{COOK}(aq) + \text{H}_2\text{O}(l) \) is written as an ionic equation, it becomes \( \text{CH}_3\text{COO}^-(aq) + \text{H}^+(aq) + \text{K}^+(aq) +\text{OH}^-(aq) \rightarrow \text{CH}_3\text{COO}^-(aq) + \text{K}^+(aq) + \text{H}_2\text{O}(l) \).
• In \( \text{H}_2\text{CO}_3(aq)+2\text{NaOH}(aq) \rightarrow \text{Na}_2\text{CO}_3(aq)+2\text{H}_2\text{O}(l) \), the ionic equation is \( 2\text{H}^+(aq)+\text{CO}_3^{2-}(aq)+2\text{Na}^+(aq)+2\text{OH}^-(aq) \rightarrow 2\text{Na}^+(aq)+\text{CO}_3^{2-}(aq)+2\text{H}_2\text{O}(l) \).
• For \( 2\text{HNO}_3(aq)+\text{Ba(OH)}_2(aq) \rightarrow \text{Ba(NO}_3)_2\text{(aq)}+2\text{H}_2\text{O}(l) \), the ionic equation is \( 2\text{H}^+(aq)+2\text{NO}_3^-(aq)+\text{Ba}^{2+}(aq)+2\text{OH}^-(aq) \rightarrow \text{Ba}^{2+}(aq)+2\text{NO}_3^-(aq)+2\text{H}_2\text{O}(l) \).

Breaking down reactions in this way allows chemists to easily identify the ions present and how they change during the reaction. It's a powerful tool for visualizing how ionic substances react in solution.

Net Ionic Equations

Net ionic equations simplify ionic equations by removing the spectator ions, showing only the ions and molecules directly involved in the reaction. These equations focus strictly on the substances that participate in the chemical change, ignoring those unchanged in the process.
For example, when we rewrite the ionic equations from the previous section into net ionic equations, we get:

• In reaction \( a) \), the net ionic equation is: \( \text{H}^+(aq) + \text{OH}^-(aq) \rightarrow \text{H}_2\text{O}(l) \).
• For reaction \( b) \) and \( c) \), they both have the net ionic equation: \( 2\text{H}^+(aq) + 2\text{OH}^-(aq) \rightarrow 2\text{H}_2\text{O}(l) \).

The net ionic equations are crucial for understanding the essence of chemical reactions in solutions. They depict only the components that undergo a chemical transformation and exclude spectator ions. This makes it easier to understand the core chemical process without unnecessary details.

Spectator Ions

Spectator ions, as the name suggests, "watch" the reaction happen without getting involved. During a chemical reaction in solution, these ions appear in the same form on both sides of an ionic equation. This means they don’t participate in the formation of the product. Their presence remains unchanged throughout the reaction.
In our examples:

• For the reaction of \( \text{CH}_3\text{COOH} \) and \( \text{KOH} \) in example \( a) \), the spectator ions are \( \text{CH}_3\text{COO}^- \) and \( \text{K}^+ \), as they remain unchanged.
• In the reaction between \( \text{H}_2\text{CO}_3 \) and \( \text{NaOH} \), \( \text{Na}^+ \) and \( \text{CO}_3^{2-} \) are the spectator ions because they appear unchanged.
• For the \( \text{HNO}_3 \) and \( \text{Ba(OH)}_2 \) reaction, the spectator ions are \( \text{Ba}^{2+} \) and \( \text{NO}_3^- \).

Identifying spectator ions is important because it streamlines understanding of chemical reactions. It clears away the "noise" of what doesn't change so that focus can place on the actual chemical transformations occurring.