Problem 43 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is the most basic oxide? (a) \(\mathrm{Al}_{2} \mathrm{O}_{3}\) (b) \(\mathrm{SeO}_{2}\) (c) \(\mathrm{Bi}_{2} \mathrm{O}_{3}\) (d) \(\mathrm{Sb}_{2} \mathrm{O}_{3}\)

Step-by-Step Solution

Answer

The most basic oxide is \( \mathrm{Bi}_{2} \mathrm{O}_{3} \).

Step 1: Understanding Basic Oxides

Basic oxides are those that react with acids to form salt and water. Generally, metal oxides are basic, especially those of the elements found on the left side of the periodic table.

Step 2: Categorizing Each Oxide

- \( \mathrm{Al}_{2} \mathrm{O}_{3} \) is an amphoteric oxide; it can react with acids and bases.- \( \mathrm{SeO}_{2} \) is an acidic oxide since it forms with a non-metal.- \( \mathrm{Bi}_{2} \mathrm{O}_{3} \) is a basic oxide, but it possesses some amphoteric characteristics.- \( \mathrm{Sb}_{2} \mathrm{O}_{3} \) is also considered an amphoteric oxide.

Step 3: Determining the Most Basic Oxide

Since \((\mathrm{Al}_{2} \mathrm{O}_{3})\) and \((\mathrm{Sb}_{2} \mathrm{O}_{3})\) are amphoteric, they are less basic compared to others. \(\mathrm{Bi}_{2} \mathrm{O}_{3}\) is the most basic out of the choices because it is the most metallic oxide available.

Key Concepts

Amphoteric Oxides

Amphoteric oxides are unique because they can react with both acids and bases. This versatility means they can behave as either acidic or basic, depending on the chemical context.
Such oxides typically belong to elements found on the staircase division of the periodic table. This division separates metals from non-metals. For example:

• Aluminum oxide (\( \mathrm{Al}_2 \mathrm{O}_3 \)) can react with hydrochloric acid (HCl) to form aluminum chloride and water.
• It can also react with sodium hydroxide (NaOH) to form sodium aluminate and water.

Understanding the behavior of amphoteric oxides is important because it helps predict how a compound will react in different environments. Recognizing these properties helps in studying the chemical behaviors of metalloids and certain metals.

Metal Oxides

Metal oxides are compounds formed between metals and oxygen. These oxides are generally basic, meaning they tend to react with acids to produce salt and water. This reaction is fundamental in many chemical syntheses and industrial applications.
Typically, metal oxides are formed by elements on the left side of the periodic table, known for their metallic characteristics.

• For instance, sodium oxide (\( \mathrm{Na}_2 \mathrm{O} \)) reacts with hydrochloric acid to form sodium chloride and water.
• Likewise, calcium oxide (\( \mathrm{CaO} \)) reacts with sulfuric acid to produce calcium sulfate and water.

The basic nature of these oxides is due to the metallic property of the elements, which tend to donate electrons easily, forming ionic bonds with oxygen. Metal oxides are often used in extracting metals, neutralizing acids, and in manufacturing glass and ceramics.

Periodic Table Trends

The periodic table is our roadmap to predicting the behavior of elements. As you move across the periodic table, several trends can be observed:
1. **Metallic Character**: Decreases as you move from left to right across a period, but increases as you move down a group. Metal oxides on the left are more basic.
2. **Acidity and Basicity of Oxides**: Elements on the left form basic oxides, while those on the right form acidic oxides. This trend is due to the increasing electronegativity as you move from metals to non-metals.

• Sodium, a metal on the far left, forms \( \mathrm{Na}_2 \mathrm{O} \), a basic oxide.
• On the contrary, sulfur on the right forms \( \mathrm{SO}_2 \), an acidic oxide.

Understanding these trends helps us predict the nature of compounds formed by various elements, which is crucial in applications ranging from industrial manufacturing to biological systems.