Problem 146 - A Complete Resource Book in Chemistry for JEE Main

Question

Which one of the following is an amphoteric oxide? [2003] (a) \(\mathrm{ZnO}\) (b) \(\mathrm{Na}_{2} \mathrm{O}\) (c) SO. (d) \(\mathrm{B}_{2} \mathrm{O}_{.}\)

Step-by-Step Solution

Answer

The amphoteric oxide is \(\mathrm{ZnO}\).

Step 1: Understand Amphoteric Oxides

Amphoteric oxides are oxides that can react with both acids and bases to form salts and water. This property distinguishes them from strictly acidic or basic oxides.

Step 2: Review the Options

Look at the given options: (a) \(\mathrm{ZnO}\), (b) \(\mathrm{Na}_{2} \mathrm{O}\), (c) SO, and (d) \(\mathrm{B}_{2} \mathrm{O}_{3}\). We need to determine which one can act as both an acid and a base.

Step 3: Evaluate Each Option

- \(\mathrm{ZnO}\) is a well-known amphoteric oxide because it can react with both acids (e.g., HCl) and bases (e.g., NaOH). - \(\mathrm{Na}_{2} \mathrm{O}\) is a basic oxide as it reacts with water to form a strong base \(\mathrm{NaOH}\). - SO is not commonly categorized as either acidic or amphoteric and seems to be incorrectly presented. - \(\mathrm{B}_{2} \mathrm{O}_{3}\) is an acidic oxide as it reacts more commonly with bases.

Step 4: Conclude Based on Review

Based on the review, the oxide from the options listed that can react with both acids and bases is \(\mathrm{ZnO}\). Therefore, \(\mathrm{ZnO}\) is the amphoteric oxide in the given options.

Key Concepts

Zinc Oxide

Zinc Oxide (ZnO) is a unique chemical compound that stands out due to its amphoteric nature. Amphoteric substances are capable of reacting with both the acidic and basic components, making them versatile.

• When ZnO reacts with hydrochloric acid (HCl), it forms zinc chloride (ZnCl_2) and water.
• When it reacts with a strong base like sodium hydroxide (NaOH), it produces sodium zincate (Na_2ZnO_2) and water.

This dual reactive nature makes zinc oxide an important compound in various industrial and chemical applications, enhancing its usefulness across fields.

Oxides and Acidity

Oxides are compounds composed of oxygen atoms bonded to other elements. They can vary significantly in their behavior based on their chemical structure, which in turn affects their reaction profiles. Some fundamental categories of oxides include:

• Acidic Oxides: These oxides form acids when they react with water. An example is sulfur dioxide (SO_2), which dissolves in water to create sulfurous acid.
• Basic Oxides: These react with water to form bases, such as sodium oxide (Na_2O), which produces NaOH.
• Amphoteric Oxides: These can react with both acids and bases, like zinc oxide (ZnO), a standout example in this category.

Understanding these types aids in grasping the broader topic of acid and base chemistry and how various oxides interact with different substances.

Acid-Base Reactions

Acid-base reactions are chemical processes that involve the transfer of protons (H+) between reactants. They are foundational to many chemical processes in nature and laboratories. Here's how they typically work:

• An acid donates a proton, becoming a conjugate base.
• A base accepts a proton, turning into a conjugate acid.

In the context of amphoteric oxides like ZnO, these reactions illustrate their remarkable flexibility. This oxide can donate or accept protons, which explains its ability to produce different salts either with acids or bases. Knowing these reactions sheds light on how different substances transform and interact.

Chemical Properties of Oxides

The chemical properties of oxides are influenced by the elements involved and their structural arrangements. These properties dictate how an oxide interacts with other chemical substances. Key chemical properties include:

• Reactivity: This involves how readily an oxide reacts with acids, bases, or water—a crucial factor in defining their application.
• Stability: Certain oxides are stable under specific conditions, while others decomposes easily, influencing their storage and handling.
• Solubility: It refers to the oxide's ability to dissolve in solvents like water, impacting its usage in aqueous solutions.

Understanding these properties helps to predict the behavior of oxides in various environments and is essential for their application in chemical synthesis, industrial processes, and learning about nature's processes.