Question

For prevention of rusting of iron, which is used in paints? (a) \(\mathrm{PbO}\) b) \(\mathrm{PbO}_{2}\) (c) \(\mathrm{Pb}_{3} \mathrm{O}_{4}\) (d) \(\mathrm{PbSO}_{4}\)

Short answer

(c) \( \mathrm{Pb}_{3} \mathrm{O}_{4} \) is used to prevent rusting in paints.

Step-by-step solution

Understand the problem

We need to identify which chemical compound, among the given options, is primarily used in paints to prevent the rusting of iron.

List properties of each compound

1. \( \mathrm{PbO} \) is Lead(II) oxide, a basic oxide mostly used in glass manufacturing.2. \( \mathrm{PbO}_{2} \) is Lead(IV) oxide, an oxidizing agent not typically used in paints. 3. \( \mathrm{Pb}_{3} \mathrm{O}_{4} \) is a form of red lead, known for its anti-corrosive properties and is commonly used in anti-rust paints. 4. \( \mathrm{PbSO}_{4} \) is Lead sulfate, not considered for rust prevention in paints.

Eliminate unsuitable options

Based on their applications, we can eliminate \( \mathrm{PbO} \), \( \mathrm{PbO}_{2} \), and \( \mathrm{PbSO}_{4} \) as they are not typically used to prevent rust in paints.

Identify the correct compound

The remaining compound \( \mathrm{Pb}_{3} \mathrm{O}_{4} \) is known for its anti-corrosive qualities and widespread use in protective paints to prevent rusting of iron.

Key concepts

Lead Compounds

Lead compounds are widely recognized in various industrial applications due to their unique chemical properties. Among these, certain lead oxides play a critical role in rust prevention for iron.

• Lead(II) Oxide (\( \text{PbO} \)) is primarily utilized in glass and ceramics manufacturing rather than in anti-rust paints. It is a basic oxide.
• Lead(IV) Oxide (\( \text{PbO}_{2} \)) is known for its strong oxidizing property. However, it is not used in rust-preventive paints because it can potentially exacerbate corrosion rather than prevent it.
• Lead(II, IV) Oxide or Red Lead (\( \text{Pb}_{3} \text{O}_{4} \)) stands out for its anticorrosive features. This compound is mainly known as red lead due to its colorful appearance. It is used extensively in paints to protect iron from rusting over time.

By understanding these individual compounds, it is easier to see why \( \text{Pb}_{3} \text{O}_{4} \) is the chosen compound for rust prevention in paints.

Anti-corrosive Paints

Anti-corrosive paints are specially formulated to prevent rust and corrosion on metal surfaces, such as iron. These paints work as a barrier against moisture and oxygen, which are two primary contributors to rusting.
Red lead oxide (\( \text{Pb}_{3} \text{O}_{4} \)) is a key ingredient in many anti-corrosive paints.

• These paints form a protective layer that is impervious to air and moisture, effectively sealing the surface of iron and thus preventing oxidation.
• They also often contain other additives to enhance durability and adherence to the metal surface, thus prolonging the lifespan of the painted object.

Employing anti-corrosive paints with compounds such as \( \text{Pb}_{3} \text{O}_{4} \) is a practical method to safeguard metal structures, vehicles, and industrial machinery, ensuring they remain free from destructive rust for a longer period.

Iron Rusting

Iron rusting is a common but problematic process affecting iron and its alloys. Rust, scientifically known as iron oxide, forms when iron reacts with oxygen and moisture present in the environment.
The chemical process can be described with the equation:\[4 \text{Fe} + 3 \text{O}_{2} + 6 \text{H}_{2}\text{O} \rightarrow 4 \text{Fe(OH)}_{3}\]This reaction leads to the flaky, reddish-brown substance we recognize as rust.To combat this:

• Preventing exposure to water and oxygen, typically through the application of anti-corrosive measures like painting with specific compounds, can significantly reduce the rate of rusting.
• Materials such as \( \text{Pb}_{3} \text{O}_{4} \), are specifically used in paints to provide an extra layer of protection.

Understanding the chemistry behind rusting helps develop effective strategies to prevent it, protecting valuable iron-based structures from deterioration.