Question

Arrange the following oxides in order of increasing acidic character: \(\mathrm{BaO}, \mathrm{Cl}_{2} \mathrm{O}_{7}, \mathrm{SO}_{3}, \mathrm{SnO}_{2}\).

Short answer

BaO < SnO2 < SO3 < Cl2O7

Step-by-step solution

Identify the Nature of Oxides

Different elements form oxides that are either basic, acidic, or amphoteric. Generally, metal oxides tend to be basic, non-metal oxides tend to be acidic, and metalloids form amphoteric oxides. This knowledge will guide us in determining whether each of these oxides is acidic, basic, or amphoteric.

Classify Each Oxide

1. **BaO (Barium Oxide)**: This is a metal oxide, thus it is typically basic. 2. **Cl2O7 (Dichlorine Heptoxide)**: A non-metal oxide, thus it is acidic. 3. **SO3 (Sulfur Trioxide)**: Another non-metal oxide, making it acidic as well. 4. **SnO2 (Tin(IV) Oxide)**: This is a metalloid oxide, so it is amphoteric.

Determine Acidic Character

Acidic character refers to the tendency of an oxide to react with water to form acids. In general, non-metal oxides (SO3, Cl2O7) are more acidic than basic metal oxides (BaO), while oxides that are amphoteric (SnO2) fall in between.

Arrange Oxides by Acidic Character

Now, arrange the oxides in the order of increasing acidic character based on our classification: 1. **Basic (Least Acidic)**: BaO 2. **Amphoteric**: SnO2 3. **Acidic**: SO3 4. **Most Acidic**: Cl2O7

Conclusion

The order of increasing acidic character is BaO < SnO2 < SO3 < Cl2O7.

Key concepts

Basic Oxides

Basic oxides are formed when metals react with oxygen. These oxides typically show basic properties, meaning they tend to react with acids to form salt and water, similar to a neutralization reaction.
Usually, when a basic oxide is dissolved in water, it forms a basic hydroxide, which has a pH greater than 7. For instance, sodium oxide (\(\text{Na}_2\text{O}\)) dissolved in water will form sodium hydroxide (\(\text{NaOH}\)), a common base.

• Metal oxides such as \(\text{BaO}\) (Barium Oxide) are considered basic.
• They are most commonly found with alkali and alkaline earth metals.
• The basicity is a result of the metallic atoms providing electrons, leading to oxide ions (\(\text{O}^{2−}\)).

These oxides are typically ionic, due to the transfer of electrons from the metal to oxygen. In a chemical reaction, basic oxides can neutralize acids and yield a salt and water as their main products. This characteristic is a hallmark of their basic nature.

Acidic Oxides

Acidic oxides are primarily composed of non-metals combined with oxygen. These oxides increase the acidic properties of solutions when dissolved in water, forming acidic substances.
Non-metal oxides, such as sulfur trioxide (\(\text{SO}_3\)) and dichlorine heptoxide (\(\text{Cl}_2\text{O}_7\)), typically react with water to form acids like sulfuric acid (\(\text{H}_2\text{SO}_4\)) and perchloric acid (\(\text{HClO}_4\)) respectively.

• Acidic oxides react with bases to form salts and water.
• They usually arise from elements with high electronegativity and small atomic radii.
• Their reactions are often exothermic when forming oxyacids with water.

These non-metallic oxides tend to form covalent bonds due to shared electrons, contributing to their acidic properties. The acidity of non-metal oxides is largely due to their ability to accept electron pairs, comparable to the behavior of acids in solution.

Amphoteric Oxides

Amphoteric oxides are unique as they showcase both basic and acidic properties, depending on the surrounding conditions. This dual characteristic allows them to react with both acids and bases to form water and salt.
Metalloids and some metals typically form amphoteric oxides, with tin(IV) oxide (\(\text{SnO}_2\)) being a classic example.

• Amphoteric oxides react with acids and bases, showcasing their unique versatility.
• They can accept or donate electrons, making them capable of participating in a variety of reactions.
• These oxides are often found at the intersection of metals and non-metals, in the periodic table, which explains their mixed properties.

Understanding amphoteric behavior unveils the bridge between distinct oxide types, highlighting the complexity of chemical reactivity. By reacting with both acidic and basic substances, these oxides demonstrate adaptability in chemical reactions, uniquely positioning them in both natural and industrial chemical processes.