Problem 74 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following oxides is solid in nature? (a) \(\mathrm{SnO}_{2}\) (b) \(\mathrm{PbO}_{2}\) (c) \(\mathrm{SiO}_{2}\) (d) all of these

Step-by-Step Solution

Answer

All of these oxides (\(\mathrm{SnO}_{2}\), \(\mathrm{PbO}_{2}\), \(\mathrm{SiO}_{2}\)) are solid in nature.

Step 1: Understand the problem

We need to determine which of the given oxides is solid in nature. The options given are \(\mathrm{SnO}_{2}\), \(\mathrm{PbO}_{2}\), \(\mathrm{SiO}_{2}\), and \("all\ of\ these"\).

Step 2: Analyze the properties of \(\mathrm{SnO}_{2}\)

\(\mathrm{SnO}_{2}\), also known as tin(IV) oxide, is a solid at room temperature. It is a white powder used in ceramics and as a reducing agent in reactions.

Step 3: Analyze the properties of \(\mathrm{PbO}_{2}\)

\(\mathrm{PbO}_{2}\) is lead(IV) oxide and is a solid at room temperature. It appears as a dark brown or black crystalline powder and is used in battery electrodes, such as in lead-acid batteries.

Step 4: Analyze the properties of \(\mathrm{SiO}_{2}\)

\(\mathrm{SiO}_{2}\), commonly known as silicon dioxide or silica, is a solid at room temperature. It is found in nature as quartz and is a major component of sand.

Step 5: Conclusion

Since \(\mathrm{SnO}_{2}\), \(\mathrm{PbO}_{2}\), and \(\mathrm{SiO}_{2}\) are all solid at room temperature, the answer is that 'all of these' oxides are solid in nature.

Key Concepts

Oxide Properties

Oxides are chemical compounds that consist of oxygen atoms bonded to atoms of another element. These compounds can exhibit a wide range of properties, largely determined by the elements bonded to oxygen. Many oxides, such as

• tin(IV) oxide (0SnO_{2}c also known as stannic oxide),
• lead(IV) oxide (bPbO_{2}c also referred to as plumbic oxide), and
• silicon dioxide (bSiO_{2}c commonly called silica),

are solids at room temperature.
The solid nature of these compounds is primarily due to their lattice structures, in which atoms are arranged in a regular pattern.
For example, bSiO_{2}c (silicon dioxide) forms a three-dimensional network of strong covalent bonds, making it exceptionally rigid.
In contrast, some oxides like

• carbon dioxide (bCO_{2}c),

are gases under normal conditions because of their simple, discrete molecular structures and weaker intermolecular forces.
Understanding oxide properties is fundamental in solid-state chemistry because they influence how materials can be used in practical applications, from ceramics to electronics.

Room Temperature Solids

At room temperature, not all chemical compounds remain solid. This behavior is influenced by their atomic bonds and molecular structure.
While many oxides such as bSnO_{2}c, bPbO_{2}c, and bSiO_{2}c are solids, some other substances exist as liquids or gases under similar conditions. These differences arise due to

• the nature and strength of the bonds between atoms,
• their molecular geometry, and
• intermolecular forces.

In solid compounds like those listed, the tightly packed atoms and the strong chemical bonds provide structural stability.
Solids are characterized by their rigidity and fixed volume.
They do not easily change shape under normal room temperature conditions.
For instance, bSiO_{2}c maintains a crystalline form due to the repeating patterns in its atomic organization, making it a prime example of a room temperature solid.
This property is significant because it affects the usability and application of these materials in various industries.

Chemical Compounds

Chemical compounds are substances formed when two or more elements are bonded together. They are represented by chemical formulas, which indicate the types and numbers of atoms present. The three common oxides mentioned

• bSnO_{2}c,
• bPbO_{2}c, and
• bSiO_{2}c,

are each different in composition but share the characteristic of containing oxygen atoms.
The properties of chemical compounds depend heavily on their bonding types. For oxides, these can include ionic, covalent, or metallic bonds, each impacting the compound's physical characteristics such as

• melting point,
• boiling point,
• solubility, and
• electrical conductivity.

For example, bSiO_{2}c is famous for its high melting point and hardness, making it excellent for use in glass and ceramics.
Understanding chemical compounds is crucial in chemistry because it allows scientists to predict not only the behavior and reactivity of materials but also to tailor materials for specific uses across fields such as materials science, biology, and environmental science.