Problem 196 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following List II (i) Anhydrous \(\mathrm{ZnCl}_{2}\) (ii) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{\theta}\) (iii) \(\mathrm{P}\) (iv) \(\mathrm{LiAlH}_{4}\) The correct matching is: The correct matching is: 1 2 3 4 (a) (ii) (iii) (iv) (i) (b) (ii) (iii) (i) (iv) (c) (iii) (ii) (iv) (i) (d) (i) (iii) (iv) (ii)

Step-by-Step Solution

Answer

Option (b) (ii) (iii) (i) (iv) matches best.

Step 1: Analyze the Given List II

The elements in List II are: (i) Anhydrous \(\mathrm{ZnCl}_{2}\), (ii) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{\theta}\), (iii) \(\mathrm{P}\), and (iv) \(\mathrm{LiAlH}_{4}\). We need to analyze the properties of each item to determine their correct position in the matching options.

Step 2: Characteristics of Each Item in List II

(i) Anhydrous \(\mathrm{ZnCl}_{2}\) is a common dehydrating agent. (ii) \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{O}^{\theta}\) is an ethoxide ion, a strong base. (iii) \(\mathrm{P}\) most commonly refers to phosphorus, which can act as a reducing agent. (iv) \(\mathrm{LiAlH}_{4}\) is a strong reducing agent used to reduce aldehydes, ketones, and other carbonyl compounds.

Step 3: Match Properties of List II to Options

Upon analyzing the properties: - Anhydrous \(\mathrm{ZnCl}_{2}\) (i) matches with the dehydrating agent role.- \(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{O}^{\theta}\) (ii) is a strong base, which can be placed typically initially in matching sequences. - \(\mathrm{P}\) (iii) as a reducing agent can fit in mid-sequence if subsequent agents further the reaction process. - \(\mathrm{LiAlH}_{4}\) (iv) fits typically towards the end of sequences involving reduction or hydride transfer.

Step 4: Choosing the Correct Matching Option

From the possible set of matches, the analysis of properties suggests: (a) (ii) (iii) (iv) (i) as a suitable match if an involved process requires a base followed by a reducing process ended by a possible dehydration.(b) (ii) (iii) (i) (iv) also offers logical order depending on reaction needs, but ends with more reduction if \(\mathrm{LiAlH}_{4}\) involves as a contractor.Comparing both alignment with typical reaction process will infer correctness of a choice without deviations noted by constraints usually sighted between (b) having correct site of dehydration earlier.

Step 5: Conclusion Based on Character Analysis

The properties and common uses of the items from List II align best with option (b) after considering their order of use in typical chemical processes.

Key Concepts

Dehydrating Agents

Dehydrating agents are substances or chemicals that facilitate the removal of water from another substance. These agents are essential in many chemical reactions, especially where the removal of water is a necessary step to drive the reaction forward or to purify a compound.

Common examples include:

• **Anhydrous Zinc Chloride (\(\mathrm{ZnCl}_{2}\))**: This agent is particularly effective due to its strong affinity for water, making it a staple in organic synthesis and purification processes.
• **Concentrated Sulfuric Acid (\(\mathrm{H}_{2}\mathrm{SO}_{4}\))**: Known for its hygroscopic nature, it draws moisture from the air or other chemicals.
• **Calcium Oxide (\(\mathrm{CaO}\))**: Often used to extract water in gas streams.

Dehydrating agents not only play crucial roles in laboratories but also find applications in industrial settings such as food preservation and chemical manufacturing.

Reducing Agents

A reducing agent is a substance that donates electrons to another compound, thereby reducing the oxidation state of that compound. They are pivotal in redox (reduction-oxidation) reactions, which involve the transfer of electrons between two species.

Some well-known reducing agents are:

• **Lithium Aluminium Hydride (\(\mathrm{LiAlH}_{4}\))**: One of the strongest reducing agents, it is commonly used to reduce aldehydes, ketones, and other carbonyl compounds.
• **Phosphorus (\(\mathrm{P}\))**: While commonly known for other applications, it can also act as a reducing agent in certain chemical reactions.
• **Hydrogen Gas (\(\mathrm{H}_{2}\))**: Often used in industrial processes for reducing metal oxides to metals.

Reducing agents find their uses in areas ranging from organic synthesis to metallurgy. Understanding their role helps chemists devise reactions needed for various synthetic processes.

Strong Bases

Strong bases are substances that can completely dissociate in water to release a significant number of hydroxide ions (\(\mathrm{OH}^{-}\)). These ions make them powerful in neutralizing acids and facilitating chemical reactions that require a strong alkaline environment.

Examples of strong bases include:

• **Sodium Hydroxide (\(\mathrm{NaOH}\))**: Widely used in industrial applications like soap making and cleaning agents.
• **Potassium Hydroxide (\(\mathrm{KOH}\))**: Similar to sodium hydroxide, it is used in a variety of industries including agriculture and manufacturing.
• **Ethoxide Ion (\(\mathrm{C}_{2}\mathrm{H}_{5}\mathrm{O}^{\theta}\))**: Formed from ethanol, it's a strong base used in various organic syntheses.

By leveraging the properties of strong bases, chemists can initiate reactions that are otherwise challenging, especially in organic chemistry where deprotonation is often necessary.