Problem 4 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is a highly corrosive salt? (a) \(\mathrm{FeCl}_{2}\) (b) \(\mathrm{HgCl}_{2}\) (c) \(\mathrm{PbCl}_{2}\) (d) \(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\)

Step-by-Step Solution

Answer

HgCl_2 (option b) is the highly corrosive salt.

Step 1: Identify Properties of Option (a)

FeCl_2, or Iron(II) chloride, is soluble in water and can behave as a weak acid in an aqueous solution, but it is not known to be highly corrosive.

Step 2: Identify Properties of Option (b)

HgCl_2, or Mercury(II) chloride, is a highly corrosive substance. It is toxic and used sometimes in disinfection and preservative applications, but its corrosiveness is a prominent property.

Step 3: Identify Properties of Option (c)

PbCl_2, or Lead(II) chloride, is not very soluble in water and is not highly corrosive. It is a dangerous lead compound but not primarily for its corrosiveness.

Step 4: Identify Properties of Option (d)

Hg2Cl2, or Mercury(I) chloride (Calomel), is not very soluble in water and is not considered highly corrosive, unlike HgCl_2.

Step 5: Conclusion

Based on the corrosive properties of the salts provided, HgCl_2 (option b) is the one that is highly corrosive.

Key Concepts

Chemical Properties

Chemical properties define how substances behave and interact with others. These include reactivity, acidity, and flammability. When we talk about corrosive salts, we are interested in how they react, especially with water and metals.

In the original exercise, we see different chloride salts like

• FeCl ₂ (Iron(II) chloride)
• HgCl ₂ (Mercury(II) chloride)
• PbCl ₂ (Lead(II) chloride)
• Hg ₂ Cl ₂ (Mercury(I) chloride)

Their chemical properties differ.

• FeCl ₂ is mildly acidic when dissolved in water but isn’t very dangerous.
• HgCl ₂, on the other hand, is highly toxic and corrosive. It can cause significant damage to tissues and materials.
• PbCl ₂ and Hg ₂ Cl ₂ are less reactive in similar contexts.

Understanding these properties helps predict how a chemical will behave in different environments or applications. This knowledge is crucial in selecting materials for laboratory setups or during transportation.

Inorganic Chemistry

Inorganic chemistry deals with compounds that are not primarily based on carbon. This encompasses salts, metals, and minerals. Chloride salts, such as those in the exercise, are a classic example.

Inorganic compounds, like HgCl ₂ and PbCl ₂, show how different elements combine to form stable or reactive structures. These salts often involve a metal and a non-metal.

• HgCl ₂ demonstrates intense corrosiveness due to mercury, a metal known for its reactivity in halide forms.
• Lead chloride, while dangerous due to lead's toxicity, displays different solubility properties.
• Compounds like these make inorganic chemistry fascinating by illustrating diverse chemical behaviors and properties.

Studying reactions and behaviors of such salts allows chemists to develop new materials and understand environmental impacts.

Safety in Chemistry

Safety should always be a priority, especially in chemistry where substances can be hazardous. Mercury(II) chloride, identified as a highly corrosive salt, is a perfect case for discussing safety.

When handling HgCl ₂, protective gear such as gloves and goggles is essential to prevent skin and eye contact. Ensure proper ventilation to avoid inhaling dangerous fumes.

Given its toxicity and corrosiveness, it’s important to follow strict protocols:

• Use fume hoods when working with volatile or highly reactive compounds.
• Properly label all chemical containers to avoid accidental misuse.
• Dispose of waste appropriately, adhering to local regulations to prevent environmental damage.

Understanding the chemical and physical hazards of compounds in advance helps ensure the safety of everyone involved in chemical processes or research.