Question

Write a balanced net ionic equation for the reaction of the amphoteric oxide \(\mathrm{Ga}_{2} \mathrm{O}_{3}\) with: (a) Aqueous sulfuric acid (b) Aqueous potassium hydroxide; the product is \(\mathrm{Ga}(\mathrm{OH})_{4}\)

Short answer

(a) \( \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 6\mathrm{H}^{+}(aq) \rightarrow 2\mathrm{Ga}^{3+}(aq) + 3\mathrm{H}_{2}O(l) \) (b) \( \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 2\mathrm{OH}^{-}(aq) + 3\mathrm{H}_{2}O(l) \rightarrow 2\mathrm{Ga(OH)_{4}^{-}}(aq) \)

Step-by-step solution

Understand the Problem

We need to write balanced net ionic equations for the amphoteric oxide \( \mathrm{Ga}_{2} \mathrm{O}_{3} \) reacting in two scenarios: (a) with sulfuric acid \( \mathrm{H}_{2}\mathrm{SO}_{4} \), and (b) with potassium hydroxide \( \mathrm{KOH} \). Amphoteric oxides can react with both acids and bases.

Identify Reactions

When an amphoteric oxide like \( \mathrm{Ga}_{2} \mathrm{O}_{3} \) reacts with an acid, it forms a salt and water. With a base, it forms a complex anion. Identify these products during reactions to help form the ionic equations.

Write Complete Ionic Equations

For (a), when \( \mathrm{Ga}_{2} \mathrm{O}_{3} \) reacts with \( \mathrm{H}_{2}\mathrm{SO}_{4} \), the complete ionic equation is: \[ \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 3\mathrm{H}_{2}\mathrm{SO}_{4}(aq) \rightarrow 2\mathrm{Ga}^{3+}(aq) + 3\mathrm{SO}_{4}^{2-}(aq) + 3\mathrm{H}_{2}O(l) \] For (b), with \( \mathrm{KOH} \), the complete ionic equation is: \[ \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 2\mathrm{OH}^{-}(aq) + 3\mathrm{H}_{2}O(l) \rightarrow 2\mathrm{Ga(OH)_{4}^{-}}(aq) \]

Determine Net Ionic Equations

In the net ionic equation, remove spectator ions. For (a), sulfate ions \( \mathrm{SO}_{4}^{2-} \) are the spectators.The net ionic equation is: \[ \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 6\mathrm{H}^{+}(aq) \rightarrow 2\mathrm{Ga}^{3+}(aq) + 3\mathrm{H}_{2}O(l) \]For (b), the complex ion is formed directly, and no removal of spectator ions is needed.The net ionic equation is:\[ \mathrm{Ga}_{2}\mathrm{O}_{3}(s) + 2\mathrm{OH}^{-}(aq) + 3\mathrm{H}_{2}O(l) \rightarrow 2\mathrm{Ga(OH)_{4}^{-}}(aq) \]

Verify Balance and Conditions

Ensure all equations are balanced in terms of both mass and charge. The number of atoms on both our charges on both sides must be equal. - For (a), 2 Gallium, 6 Hydrogens, and 3 Oxygens are balanced. - For (b), charges (-2) and all atoms including Gallium, Hydrogen, and Oxygen are balanced.

Key concepts

Amphoteric Oxides

Amphoteric oxides are unique chemical compounds that can react with both acids and bases. This dual-reactivity makes them fascinating and useful in various chemical processes. An example of such a compound is gallium(III) oxide, represented as \( \mathrm{Ga}_2 \mathrm{O}_3 \).

When an amphoteric oxide reacts with an acid, it generally leads to the formation of a salt and water. Conversely, when it reacts with a base, it often results in the formation of a complex ion. This means amphoteric oxides adapt their behavior based on the nature of the other reactant, providing versatility in chemical reactions.

Some other examples of amphoteric oxides include aluminum oxide \( \mathrm{Al}_2 \mathrm{O}_3 \) and zinc oxide \( \mathrm{ZnO} \). Recognizing these properties is key in writing and understanding balanced chemical equations, especially net ionic equations.

Reaction with Acids and Bases

Amphoteric oxides like \( \mathrm{Ga}_2 \mathrm{O}_3 \) display distinct reactions with acids and bases due to their ability to react as either a Lewis acid or a base.

In the reaction with sulfuric acid \( \mathrm{H}_2\mathrm{SO}_4 \), \( \mathrm{Ga}_2 \mathrm{O}_3 \) behaves as a base. It reacts to form gallium ions \( \mathrm{Ga}^{3+} \) and water, which can be observed in the net ionic equation:

• \[ \mathrm{Ga}_2 \mathrm{O}_3(s) + 6 \mathrm{H}^+(aq) \rightarrow 2 \mathrm{Ga}^{3+}(aq) + 3\mathrm{H}_2\mathrm{O}(l) \]

This reaction highlights how the oxide donates electrons to acidic protons, resulting in water and metal ions.

When \( \mathrm{Ga}_2 \mathrm{O}_3 \) reacts with potassium hydroxide \( \mathrm{KOH} \), it acts as an acid. Here, \( \mathrm{Ga}_2 \mathrm{O}_3 \) accepts electrons, leading to the formation of a complex anion \( \mathrm{Ga(OH)}_4^- \):

• \[ \mathrm{Ga}_2 \mathrm{O}_3(s) + 2\mathrm{OH}^-(aq) + 3\mathrm{H}_2\mathrm{O}(l) \rightarrow 2\mathrm{Ga(OH)}_4^-(aq) \]

This reveals the oxide's ability to adapt and form complex structures when presented with bases.

Equation Balancing

Balancing chemical equations is fundamental in chemistry because it reflects the conservation of mass and charge. Every reaction must have the same number of each type of atom on both sides, as well as an equal total charge. Creating balanced equations is crucial for understanding the full scope of chemical reactions.

When balancing net ionic equations, one must first derive complete ionic equations and identify spectator ions, which do not participate in the overall reaction. For instance, in the reaction between \( \mathrm{Ga}_2 \mathrm{O}_3 \) and \( \mathrm{H}_2\mathrm{SO}_4 \):

• The complete ionic equation might initially list all ions, but careful analysis reveals that sulfate ions \( \mathrm{SO}_4^{2-} \) do not change during the reaction.
• Removing these spectator ions leads to a simplified, balanced net ionic equation.

Always verify that both the mass and charge are balanced by ensuring the number of each atom on both sides of the equation is equal, and the charges on each side are identical.
These practices enable chemists to accurately represent reactions, making it easier for others to understand and predict outcomes.