Problem 46 - A Complete Resource Book in Chemistry for JEE Main

Question

The number of \(\mathrm{P}-\mathrm{O}-\mathrm{P}\) bonds in cyclic metaphosphoric acid is (a) zero (b) two (c) three (d) four

Step-by-Step Solution

Answer

The number of P-O-P bonds in cyclic metaphosphoric acid is three.

Step 1: Understanding the Problem

Cyclic metaphosphoric acid is a compound with a specific ring structure involving phosphorus and oxygen atoms. We need to identify how many P-O-P bonds are present in this structure.

Step 2: Structure of Cyclic Metaphosphoric Acid

Cyclic metaphosphoric acid, often represented as (HPO_3)_n, typically exists as a ring. A common ring form is a trimer where n=3, which results in a cycle with alternating phosphoric and oxygen atoms.

Step 3: Visualizing the Trimer

In the trimer form of cyclic metaphosphoric acid, the structure consists of three phosphorus (P) atoms and three repeating metaphosphate units (PO_3), connected to form a closed loop. Each phosphorus atom is bonded to adjacent oxygen atoms which then connect to the next phosphorus.

Step 4: Counting the P-O-P Bonds

In this cyclic structure, each phosphorus atom forms two P-O-P bonds with neighboring phosphorus atoms through shared oxygen atoms. Since the structure is a closed ring with three phosphorus atoms, there are exactly three such P-O-P bonds.

Key Concepts

Understanding P-O-P Bonds

P-O-P bonds are a fundamental feature in cyclic metaphosphoric acid that links phosphorus and oxygen in a ring structure. In simple terms, these bonds connect two phosphorus atoms through an oxygen atom. They are commonly seen in phosphorus-based compounds like phosphates and related structures.

These bonds are significant because they help form the backbone of the cyclic phosphoric structures. Each P-O-P bond consists of one oxygen atom linked to two phosphorus atoms, creating a bridge between them. In a cyclic metropolitan acid structure, these bonds ensure continuity and closure of the cycle.

• P-O-P bonds serve as key connections within the molecule's network.
• They play a crucial role in maintaining the structural integrity of cyclic molecules.
• Such bonds are particularly important for cyclic structures like metaphosphoric acids.

Exploring the Trimer Structure

A trimer structure in chemistry is essentially a molecular formation comprising three repeating units connected in a series. For cyclic metaphosphoric acid, the trimer structure involves three phosphorus atoms, each linked through oxygen atoms to create a closed loop.

In the case of cyclic metaphosphoric acid, the chemical notation (HPO_3)_3 refers to this trimer configuration. Think of it as a triangle, where each corner represents a metaphosphate unit, and each side symbolizes a P-O bridging bond.

• The trimer is the smallest cyclic structure of metaphosphoric acid.
• Each unit (HPO_3) in the trimer is a metaphosphate group contributing to the formation of the cyclic pattern.
• This structure highlights the organization and precise repeating nature of the metaphosphoric acid rings.

The Ring Structure of Phosphoric Acids

The ring structure is a definitive characteristic of metaphosphoric acids and is crucial for understanding their chemical behavior. Simply put, the ring structure consists of repeating units of (HPO_3) linked in a circular arrangement.

In cyclic metaphosphoric acids, these rings can vary in size but are most commonly observed as trimers, as in the example above. This closed-loop formation ensures stability, allowing for consistent chemical properties and reactivity. The ring consists of alternating phosphorus and oxygen atoms, leading to the formation of P-O-P- bonds and completing the ring circuit.

• The ring structure is vital for maintaining the unique properties of metaphosphoric acids.
• Such rings make the acid more stable and give rise to distinctive reactivity compared to linear structures.
• Understanding these rings provides insight into the potential applications and functions of cyclic metaphosphoric acids in various chemical reactions.