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

Statement (b) is correct.

Step 1: Understanding Anhydrides

An anhydride is a compound formed from another compound by the removal of water. Therefore, for a compound like \( \mathrm{ClO}_2 \) to be the anhydride of \( \mathrm{HClO}_2 \) and \( \mathrm{HClO}_3 \), the addition of water should yield either \( \mathrm{HClO}_2 \) or \( \mathrm{HClO}_3 \). \( \mathrm{ClO}_2 \) is actually the anhydride of \( \mathrm{HClO}_2 \), as adding water to \( \mathrm{ClO}_2 \) would form this acid. Thus, statement (a) is partially correct, as it does not form \( \mathrm{HClO}_3 \).

Step 2: Analyzing Iodine Pentoxide Usage

\( \mathrm{I}_2 \mathrm{O}_5 \) is commonly used in the laboratory for the quantitative estimation of carbon monoxide (\( \mathrm{CO} \)) because it readily oxidizes carbon monoxide to carbon dioxide. This makes statement (b) correct.

Step 3: Examining Uses of Chlorine Oxides

Both \( \mathrm{Cl}_2 \mathrm{O} \) and \( \mathrm{ClO}_2 \) are known to be used as bleaching agents due to their strong oxidizing properties. \( \mathrm{ClO}_2 \), in particular, is used as a disinfectant (germicide) in water treatment. Thus, statement (c) is correct.

Step 4: Verifying Overall Accuracy

Statement (a) has inaccuracies, but both statements (b) and (c) are correct. Therefore, statement (d) which claims all are correct, cannot be true.

Key Concepts

Anhydride

In inorganic chemistry, an `anhydride` refers to a compound derived from another compound by the removal of water molecules. For instance, the compound \( \mathrm{ClO}_2 \) is considered the anhydride of \( \mathrm{HClO}_2 \), because when you add water to \( \mathrm{ClO}_2 \), you obtain \( \mathrm{HClO}_2 \).
It's noteworthy that \( \mathrm{ClO}_2 \) does not form \( \mathrm{HClO}_3 \) upon hydration, so it's incorrect to call it an anhydride of both acids. Always remember, anhydrides are often connected to acids and can be formed by the removal of a single water molecule from polybasic acids.

Oxidation

`Oxidation` is a chemical process involving the loss of electrons by a molecule, atom, or ion. In the exercise, \( \mathrm{I}_2 \mathrm{O}_5 \), also known as iodine pentoxide, acts as an oxidizing agent. It oxidizes carbon monoxide (\( \mathrm{CO} \)) to carbon dioxide (\( \mathrm{CO}_2 \)).
This reaction is valuable in quantitative estimation practices, as it allows for the precise determination of \( \mathrm{CO} \) presence by measuring the resulting \( \mathrm{CO}_2 \). Key to oxidation processes is the role of oxidizing agents, which accept electrons and facilitate the transformation of other substances.

Bleaching agents

`Bleaching agents` are substances that remove color by breaking down chromophore structures. Both \( \mathrm{Cl}_2 \mathrm{O} \) and \( \mathrm{ClO}_2 \) are used as bleaching agents due to their effective oxidizing properties.
They work by oxidizing the colored substances into colorless forms. Chlorine-based bleaching agents are widely used in various industries, such as paper and textile manufacturing. Their ability to oxidize quickly ensures efficient and effective bleaching, but it is important to handle them with care due to their reactivity.

Germicide

A `germicide` is an agent that kills microorganisms, making it a critical component in maintaining hygiene and preventing infections. \( \mathrm{ClO}_2 \) is particularly effective as a germicide. In water treatment processes, \( \mathrm{ClO}_2 \) ensures water is safe for consumption by destroying harmful pathogens.
Its high efficiency and low production of harmful by-products make \( \mathrm{ClO}_2 \) a preferred choice over other disinfectants. This strong oxidizing property of \( \mathrm{ClO}_2 \) allows it to serve dual purposes as both a bleaching agent and a disinfectant in various fields.

Quantitative Estimation

`Quantitative estimation` involves the measurement of the amount or concentration of a chemical compound or element. In the context of the exercise, \( \mathrm{I}_2 \mathrm{O}_5 \) is used to estimate the concentration of carbon monoxide by oxidizing it to carbon dioxide.
This method is precise as the reaction is stoichiometric and easy to detect the resultant \( \mathrm{CO}_2 \) formation. Measuring the exact quantity of a chemical in a solution is crucial in fields such as environmental monitoring, pharmaceuticals, and quality control in manufacturing. Quantitative estimation techniques often rely on reactions with a known stoichiometry to provide accurate readings.