Question

Some metal oxides, such as \(\mathrm{Sc}_{2} \mathrm{O}_{3}\), do not react with pure water, but they do react when the solution becomes either acidic or basic. Do you expect \(\mathrm{Sc}_{2} \mathrm{O}_{3}\) to react when the solution becomes acidic or when it becomes basic? Write a balanced chemical equation to support your answer.

Short answer

Scandium oxide (Sc2O3) will react with an acidic solution, as it can accept protons from H+ ions. It will not react with a basic solution, as there are no available protons to donate. The balanced chemical equation for the reaction with an acidic solution is: \(Sc2O3(s) + 6H^+(aq) → 2Sc^{3+}(aq) + 3H2O(l)\)

Step-by-step solution

Identify acidic and basic solutions

An acidic solution is one that contains more H+ ions, while a basic solution contains more OH- ions. In an acidic solution, the reaction will involve the donation of protons (H+) to Sc2O3, while in a basic solution, Sc2O3 will donate protons to the OH- ions. Let's analyze each case.

Case 1: Reaction with an acidic solution

An acidic solution contains H+ ions (or H3O+ ions). So the reaction between Sc2O3 and an acidic solution might look like: Sc2O3(s) + H+(aq) → ? Scandium oxide might accept protons as it has a basic oxide ion (O2-). So, the reaction between Sc2O3 and an acidic solution would produce scandium ions and water: Sc2O3(s) + 6H+(aq) → 2Sc3+(aq) + 3H2O(l)

Case 2: Reaction with a basic solution

Considering a basic solution contains OH- ions, the reaction between Sc2O3 and a basic solution might look like: Sc2O3(s) + OH-(aq) → ? Since Sc2O3 already contains oxide ions (O2-), there are no available protons to donate. Thus, Sc2O3 will not react with a basic solution.

Conclusion

Scandium oxide (Sc2O3) will react with an acidic solution, and the balanced chemical equation for the reaction is: Sc2O3(s) + 6H+(aq) → 2Sc3+(aq) + 3H2O(l)

Key concepts

Acid-Base Reactions

Acid-base reactions are fundamental chemical processes where an acid donates protons (\(\text{H}^+\) ions) and a base accepts protons. This interaction generally leads to the formation of a salt and water. When considering how a metal oxide like \(\mathrm{Sc}_2\mathrm{O}_3\) will react, it is important to recognize its role as a basic oxide.

• In an acidic solution, these reactions are driven by the availability of \(\text{H}^+\) ions. The protons are donated to the oxide ions present in the metal oxide, facilitating a chemical reaction.
• In a basic solution, however, the presence of \(\text{OH}^-\) ions implies a lack of available protons for the metal oxide to interact with, typically resulting in a lack of reaction.

So in this scenario of scandium(III) oxide, \(\text{Sc}_2\text{O}_3\), it does indeed react with acids since it can accept protons from the acidic medium, but it does not react in a basic environment where no such interchange occurs.

Balanced Chemical Equation

Writing a balanced chemical equation is essential in accurately representing the details of a chemical reaction. It helps to visualize both the reactants and products involved while respecting the law of conservation of mass. To balance a chemical equation, you must ensure that the same number of each type of atom appears on both sides of the equation. For the reaction between \(\mathrm{Sc}_2\mathrm{O}_3\) and an acidic solution:1. **Begin with the unbalanced equation:** \(\mathrm{Sc}_2\mathrm{O}_3(s) + \mathrm{H}^+(aq) \rightarrow \mathrm{Sc}^{3+}(aq) + \mathrm{H}_2\mathrm{O}(l)\) 2. **Count the atoms of each type on both sides:** - Reactants: 2 scandium, 3 oxygen, x hydrogen - Products: 2 scandium (\(2 \times \mathrm{Sc}^{3+}\)), 3 oxygen, x water3. **Balance the equation by adjusting coefficients:** - You need 6 hydrogen ions to properly combine with the oxygen atoms to form 3 water molecules. - The balanced chemical equation is: \(\mathrm{Sc}_2\mathrm{O}_3(s) + 6\mathrm{H}^+(aq) \rightarrow 2\mathrm{Sc}^{3+}(aq) + 3\mathrm{H}_2\mathrm{O}(l)\) This equation demonstrates the conservation of mass and charge across the chemical reaction involving scandium oxide and hydrochloric acid.

Reactivity of Metal Oxides

Metal oxides, like \( \mathrm{Sc}_2\mathrm{O}_3 \), vary in their reactivity based on their composition and the solution they are introduced into. Understanding their reactivity involves recognizing their capability of donating or accepting protons depending on the context of the reaction.

• **Basic Metal Oxides:** These typically react well with acids. They have oxide ions (\(O^{2-}\)) that can accept \(H^+\) ions, forming water and a salt.
• **Amphoteric Oxides:** Some oxides can react with both acids and bases, although scandium oxide does not fall into this category.
• **Non-Reacting Contexts:** When a basic oxide like \(\text{Sc}_2\text{O}_3\) is in contact with a basic environment, the lack of \(\text{H}^+\) ions means it typically doesn’t engage in any notable reaction due to the absence of an appropriate reaction partner.

The evaluation of metal oxide reactivity is crucial in predicting and understanding chemical behavior in diverse settings, particularly in industrial and environmental chemistry.