Problem 162 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following (a) Aqueous solution of (p) Anhydrone \(\mathrm{NaOCl}\) (b) \(\mathrm{KClO}_{3}\) (q) Javelle water (c) \(\mathrm{Mg}\left(\mathrm{ClO}_{4}\right)_{2}\) (r) Euchlorine (d) \(\mathrm{Cl}_{2}\) and \(\mathrm{ClO}_{2}\) mixture (s) Berthelot's salt

Step-by-Step Solution

Answer

(a) - (q), (b) - (s), (c) - (p), (d) - (r)

Step 1: Match Aqueous Solution of NaOCl

The aqueous solution of sodium hypochlorite, NaOCl, is commonly known as bleach or Javelle water. Thus, match (a) with (q) Javelle water.

Step 2: Match KClO3

Potassium chlorate, KClO3, is known as Berthollet's salt. Therefore, match (b) with (s) Berthollet's salt.

Step 3: Match Mg(ClO4)2

Magnesium perchlorate, Mg(ClO4)2, is a very effective desiccant, also known as anhydrone due to its property of absorbing water. Therefore, match (c) with (p) Anhydrone.

Step 4: Match Cl2 and ClO2 Mixture

A mixture of Cl2 (chlorine) and ClO2 (chlorine dioxide) was historically referred to as Euchlorine. Hence, match (d) with (r) Euchlorine.

Key Concepts

Chemical Nomenclature

Chemical nomenclature is the systematic naming of chemical compounds. This allows chemists to identify substances by a standard name across all languages and regions. In the nomenclature for inorganic compounds, different rules apply based on the types of ions involved.

• Ionic Compounds: These consist of a metal and a non-metal ion, such as sodium hypochlorite (NaOCl). Here, the metal (sodium) keeps its name as it is, while the non-metal ion (hypochlorite) is named based on its chemical structure.
• Covalent Compounds: These are formed between non-metals. An example is chlorine dioxide (ClO₂), where prefixes like "mono-", "di-", "tri-" indicate the number of each element.

The names often hint at a compound's properties, making nomenclature a useful tool in chemistry.

Aqueous Solutions

Aqueous solutions are those in which a substance is dissolved in water. For example, sodium hypochlorite (NaOCl) in water is what we commonly refer to as bleach. This solution has powerful oxidizing properties and is widely used for disinfection.
Water, being a polar solvent, dissolves many ionic and molecular compounds due to its ability to form hydrogen bonds. In aqueous solutions:

• Dissociation: Ionic compounds like NaOCl dissociate into their component ions, such as Na⁺ and OCl^-.
• Solvent Properties: Water can stabilize different ions, making it an excellent medium for reactions.

Understanding aqueous solutions is crucial in fields such as medicine, environmental science, and industrial chemistry.

Chemical Formulas

Chemical formulas provide the ratio of atoms in the compound and are crucial for understanding the composition of substances. They are classified into empirical formulas and molecular formulas.

• Empirical Formula: Shows the simplest whole-number ratio of atoms in a compound. For instance, the empirical formula for hydrogen peroxide is HO, while its molecular formula is H₂O₂.
• Molecular Formula: Details the exact number of each type of atom in a molecule, such as potassium chlorate (KClO₃), which indicates one potassium, one chlorine, and three oxygen atoms.

The chemical formula also aids in determining the structure and potential reactions of the compounds.

Oxidizing Agents

Oxidizing agents are substances that gain electrons in a chemical reaction, becoming reduced while the other substance gets oxidized. They are essential in many chemical processes. Examples include oxygen, chlorine, and compounds like sodium hypochlorite.
In redox reactions (reduction-oxidation reactions):

• Oxidizer Role: Substances like NaOCl can oxidize other compounds, causing the loss of electrons. This is why NaOCl is effective as a bleaching and disinfecting agent.
• Applications: Oxidizing agents are used in water treatment, sterilization, and as powerful cleaning agents due to their ability to break down substances.

Knowing which substances are good oxidizers helps in predicting chemical reactions and understanding their applications in everyday life and industry.