Problem 6 - Chemistry in 30 days

Question

Which oxide reacts with both \(\mathrm{HCl}\) and \(\mathrm{NaOH}\) (a) \(\mathrm{CO}_{2}\) (b) \(\mathrm{CaO}\) (c) \(\mathrm{N}_{2} \mathrm{O}_{5}\) (d) \(\mathrm{ZnO}\)

Step-by-Step Solution

Answer

(d) \( \mathrm{ZnO} \) is the oxide that reacts with both \( \mathrm{HCl} \) and \( \mathrm{NaOH} \).

Step 1: Understanding the Question

We need to determine which oxide listed can react with both \( \mathrm{HCl} \) (a strong acid) and \( \mathrm{NaOH} \) (a strong base). Such a substance that reacts with both acids and bases is called an amphoteric oxide.

Step 2: Identifying the Nature of Each Oxide

Let's consider the chemical nature of each oxide listed. - \( \mathrm{CO}_2 \): A non-metallic oxide, acidic in nature.- \( \mathrm{CaO} \): A metallic oxide, basic in nature.- \( \mathrm{N}_2 \mathrm{O}_5 \): A non-metallic oxide, acidic in nature.- \( \mathrm{ZnO} \): A metallic oxide known to exhibit amphoteric behavior.

Step 3: Confirm Reaction with Both Acid and Base

Among these, only \( \mathrm{ZnO} \) shows amphoteric behavior.- \( \mathrm{ZnO} + 2\mathrm{HCl} \rightarrow \mathrm{ZnCl}_2 + \mathrm{H}_2\mathrm{O} \) (Reaction with acid)- \( \mathrm{ZnO} + 2\mathrm{NaOH} \rightarrow \mathrm{Na}_2[\mathrm{Zn(OH)}_4] \) (Reaction with base)This confirms that \( \mathrm{ZnO} \) reacts with both \( \mathrm{HCl} \) and \( \mathrm{NaOH} \).

Key Concepts

Acid-Base Reactions

In the world of chemistry, acid-base reactions are pivotal. These reactions involve the transfer of protons (hydrogen ions) between substances. Understanding which substances can participate in these reactions helps us grasp many chemical processes.
One intriguing category of substances within these reactions are amphoteric oxides. An amphoteric oxide is unique because it can act as an acid in some reactions and as a base in others.
Let's look at zinc oxide, \( \mathrm{ZnO} \), as an example:

• When \( \mathrm{ZnO} \) reacts with hydrochloric acid, \( \mathrm{HCl} \), it behaves as a base. The reaction is: \( \mathrm{ZnO} + 2\mathrm{HCl} \rightarrow \mathrm{ZnCl}_2 + \mathrm{H}_2\mathrm{O} \).
• Conversely, when \( \mathrm{ZnO} \) reacts with sodium hydroxide, \( \mathrm{NaOH} \), it behaves as an acid: \( \mathrm{ZnO} + 2\mathrm{NaOH} \rightarrow \mathrm{Na}_2[\mathrm{Zn(OH)}_4] \).

Amphoteric behavior shows the versatile chemistry of certain oxides, especially in forming salts and neutralizing both acids and bases.

Chemical Reactions

Chemical reactions are events where substances change their structures to form new ones. Reactants, the starting substances, undergo transformations to become products. The concepts of acids, bases, and amphoteric behavior broaden our understanding of these transformations.
Each type of oxide reacts differently based on its chemical nature. Metallic oxides like \( \mathrm{CaO} \) generally react with acids to form salts and water. In contrast, non-metallic oxides like \( \mathrm{CO}_2 \) react with water to form acids, indicative of their particular roles in reaction dynamics.
When predicting the products of a chemical reaction, it's crucial to know the properties of the substances involved. For instance:

• Basic oxides react with acids to furnish salts and water, for example, \( \mathrm{CaO} + 2\mathrm{HCl} \rightarrow \mathrm{CaCl}_2 + \mathrm{H}_2\mathrm{O} \).
• Non-metallic oxides typically don't react with bases in the way amphoteric oxides do.

This knowledge helps predict and balance chemical equations, a critical skill in chemistry education.

Chemistry Education

Chemistry education aims at simplifying complex concepts for students, making them engaging and practical. It involves not just rote learning but understanding principles behind chemical reactions and behaviors, such as the dual nature of amphoteric substances.
To deeply understand topics like amphoteric oxides, students should explore chemical equations and conduct experiments. This practical experience can reinforce their learning by providing concrete examples of theoretical concepts.
Teachers can use multimedia resources, demonstrations, and interactive problem-solving sessions to invigorate the learning process. When students connect with real-world examples and applications, their grasp of these concepts becomes stronger.
For instance:

• Visualizing reactions using molecular model kits to see how atoms rearrange during chemical reactions.
• Experimenting with substances such as \( \mathrm{ZnO} \) in lab sessions to observe firsthand its reactions with acids and bases.

This active engagement promotes a comprehensive understanding of chemistry, preparing students for more complex topics ahead.