Problem 135 - A Complete Resource Book in Chemistry for JEE Main

Question

Among the following, the number of compounds than can react with \(\mathrm{PCl}_{5}\) to give \(\mathrm{POCl}_{3}\) is \(\mathrm{O}_{2}, \mathrm{CO}_{2}, \mathrm{SO}_{2}\), \(\mathrm{H}_{2} \mathrm{O}, \mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{P}_{4} \mathrm{O}_{10}\)

Step-by-Step Solution

Answer

Three compounds: \(\text{SO}_2\), \(\text{H}_2\text{O}\), and \(\text{P}_4\text{O}_{10}\).

Step 1: Identify Reaction Pairs

To solve this problem, we need to identify compounds that react with \( \text{PCl}_5 \) to form \( \text{POCl}_3 \). Typically, \( \text{PCl}_5 \) reacts with compounds that contain oxygen atoms that can contribute to the formation of \( \text{POCl}_3 \).

Step 2: Analyze Each Compound

Now, evaluate each compound to determine if it reacts with \( \text{PCl}_5 \) to form \( \text{POCl}_3 \): \( \text{O}_2 \), \( \text{CO}_2 \), \( \text{SO}_2 \), \( \text{H}_2\text{O} \), \( \text{H}_2\text{SO}_4 \), and \( \text{P}_4\text{O}_{10} \).

Key Concepts

Phosphorus Pentachloride

Phosphorus Pentachloride, or \( \text{PCl}_5 \), is a key reagent often used in inorganic chemistry. It is composed of phosphorus and chlorine atoms, forming a compound that is highly reactive due to its ability to act as a chlorinating agent.
Phosphorus Pentachloride has a trigonal bipyramidal structure, which allows it to accept electron pairs from oxygen-containing compounds. When \( \text{PCl}_5 \) interacts with such compounds, it induces chemical changes that can lead to the formation of different phosphorus oxychloride compounds, such as \( \text{POCl}_3 \).
\( \text{PCl}_5 \) is known for its role in organic and inorganic synthesis processes, including converting alcohols into alkyl halides or reacting with water or other oxygen-donating compounds to yield useful products.

Phosphoryl Chloride

Phosphoryl Chloride, represented as \( \text{POCl}_3 \), is a significant phosphorus compound resulting from reactions involving \( \text{PCl}_5 \) and oxygen-donating compounds.
\( \text{POCl}_3 \) is formed when oxygen atoms participate in reacting with the chlorinating property of \( \text{PCl}_5 \), creating a stable phosphorus-oxygen bond. This compound is primarily used as a solvent, a chlorinating agent, and a reagent in the synthesis of organophosphorus compounds.
Its formation offers insight into crucial reaction mechanisms in inorganic chemistry, as identifying which compounds it forms from highlights the importance of understanding how phosphorus compounds behave with varying reactants.

Oxygen Compound Reactivity

Compounds that react with \( \text{PCl}_5 \) to give \( \text{POCl}_3 \) have distinct characteristics related to their oxygen content. The capacity of compounds to donate oxygen atoms plays a vital role in such reactions.
For example, water \( (\text{H}_2\text{O}) \) readily reacts with \( \text{PCl}_5 \) as its oxygen atom can easily form \( \text{POCl}_3 \). Similarly, sulfur dioxide \( (\text{SO}_2) \) and phosphorus pentoxide \( (\text{P}_4\text{O}_{10}) \) are capable of reacting due to their oxygen atoms.
When evaluating the reactivity of oxygen compounds, the focus should be on the availability and nature of the oxygen atoms. This determines their potential to partake in forming new compounds with \( \text{PCl}_5 \).

Inorganic Chemistry

Inorganic chemistry is an extensive field where understanding the behavior and reaction mechanisms of non-organic substances is crucial. Here, the interactions between phosphorus pentachloride \( (\text{PCl}_5) \) and various oxygen-containing compounds underline fundamental inorganic chemistry principles.
Phosphorus and chlorine interactions are a classic example of halogen chemistry, while phosphorus reacting with oxygen-containing compounds illustrates how molecules can form new substances such as phosphoric or phosphoryl-containing compounds.
Academic exploration in inorganic chemistry not only involves identifying possible reactions, like those between \( \text{PCl}_5 \) and mentioned oxygen compounds, but also necessitates comprehending the structure and mechanism that lead to the creation of essential phosphorus oxychlorides. This knowledge assists in enhancing synthesis strategies and developing new inorganic compounds with varied applications.