Problem 68 - A Complete Resource Book in Chemistry for JEE Main

Question

Select the correct statement. (a) \(\mathrm{ClO}_{2}\) is the anhydride of \(\mathrm{HClO}_{2}\) and \(\mathrm{HClO}_{3}\) (b) \(\mathrm{I}_{2} \mathrm{O}_{5}\) is used in the quantitative estimation of \(\mathrm{CO}\) (c) \(\mathrm{Cl}_{2} \mathrm{O}\) and \(\mathrm{ClO}_{2}\) are used as bleaching agents and as germicides (d) all of the these are correct

Step-by-Step Solution

Answer

The correct statement is (b).

Step 1: Analyze Statement (a)

Statement (a) claims that \( \mathrm{ClO}_{2} \) is the anhydride of \( \mathrm{HClO}_{2} \) and \( \mathrm{HClO}_{3} \). An anhydride is a compound that forms an acid or base when combined with water. \( \mathrm{ClO}_{2} \) is the anhydride of \( \mathrm{HClO}_{2} \) but not of \( \mathrm{HClO}_{3} \). Therefore, part of the statement is incorrect.

Step 2: Analyze Statement (b)

Statement (b) claims that \( \mathrm{I}_{2} \mathrm{O}_{5} \) is used in the quantitative estimation of \( \mathrm{CO} \). \( \mathrm{I}_{2} \mathrm{O}_{5} \) is indeed used for this purpose, as it reacts with carbon monoxide (CO) quantitatively to form iodine (\( \mathrm{I}_{2} \)) which can be measured. Hence, this statement is correct.

Step 3: Analyze Statement (c)

Statement (c) suggests that \( \mathrm{Cl}_{2} \mathrm{O} \) and \( \mathrm{ClO}_{2} \) are used as bleaching agents and as germicides. Both \( \mathrm{Cl}_{2} \mathrm{O} \) and \( \mathrm{ClO}_{2} \) are known for their effectiveness in bleaching and germicidal applications; thus, this statement is correct.

Step 4: Conclusion

Since statement (a) is partially incorrect, not all statements (a, b, c) are correct. Therefore, option (d) 'all of these are correct' is incorrect.

Key Concepts

Anhydride

Anhydrides are special types of chemical compounds that transform into acids or bases when they come into contact with water. Imagine a dry sponge absorbing water and expanding; anhydrides similarly undergo a change. For instance, chloride dioxide \( \mathrm{ClO}_{2} \) is the anhydride of chlorous acid \( \mathrm{HClO}_{2} \). When \( \mathrm{ClO}_{2} \) combines with water, it becomes \( \mathrm{HClO}_{2} \). However, it is not an anhydride of chloric acid \( \mathrm{HClO}_{3} \). This distinction is important. Anhydrides play a significant role in various chemical reactions, often serving as a precursor to acidic or basic solutions. Understanding how anhydrides function can help in predicting the behavior of compounds in chemical reactions, making them a crucial part of any chemistry curriculum.

Quantitative Estimation

Quantitative estimation is a process in chemistry where the amount or concentration of a substance in a mixture is determined. This is vital for confirming the presence and measuring the exact quantity of substances such as pollutants or reactants in reactions. For example, iodine pentoxide \( \mathrm{I}_{2} \mathrm{O}_{5} \) is used for estimating carbon monoxide \( \mathrm{CO} \) levels. When \( \mathrm{I}_{2} \mathrm{O}_{5} \) reacts with \( \mathrm{CO} \), it generates iodine \( \mathrm{I}_{2} \). By measuring the amount of iodine formed, scientists can determine the original amount of carbon monoxide present. This quantitative approach ensures precision and accuracy, which are foundational in scientific experiments and environmental monitoring.

Bleaching Agents

Bleaching agents are chemicals used to whiten or lighten substances, predominantly textiles and paper, by removing color. This is typically achieved through a chemical reaction that breaks down colored compounds into colorless ones. Chlorine-based agents like \( \mathrm{Cl}_{2} \) and chlorine dioxide \( \mathrm{ClO}_{2} \), are widely used because of their effectiveness.

• They react with colored substances to decolorize them.
• They help in maintaining the whiteness of fabrics and papers.

Understanding the chemistry of bleaching agents allows for safe and efficient use in both industrial and household settings.

Germicides

Germicides are chemical agents capable of killing microorganisms and are essential in maintaining hygiene and preventing the spread of diseases. They are used in a variety of settings, from household disinfectants to medical facilities. Compounds like \( \mathrm{Cl}_{2} \) and \( \mathrm{ClO}_{2} \) act as powerful germicides. Their mode of action involves:{

• Disrupting the cell walls of bacteria.
• Inactivating viruses thus sterilizing surfaces and water.

When used correctly, these germicides effectively control microbial growth, ensuring safer environments for us all.