Problem 204 - A Complete Resource Book in Chemistry for JEE Main

Question

The number of hydrogen atom(s) attached to phosphorous atom in hypophosphorous acid is \(\quad\) (a) zero (b) two (c) one (d) three

Step-by-Step Solution

Answer

b) two

Step 1: Understand Hypophosphorous Acid

Hypophosphorous acid is commonly represented by the chemical formula \( H_3PO_2 \). It contains phosphorus, hydrogen, and oxygen atoms.

Step 2: Identify the Structure

The chemical structure of hypophosphorous acid can be represented as HOP(O)H_2. It consists of one phosphorus atom, two oxygen atoms, and three hydrogen atoms.

Step 3: Analyze the Bonding

In the structure HOP(O)H_2, observe that the phosphorus atom is directly bonded to two hydrogen atoms.

Step 4: Count the Hydrogen Atoms Attached to Phosphorous

Directly count only the hydrogen atoms attached to the phosphorus atom, which are two.

Key Concepts

Chemical Structure

Understanding the chemical structure of hypophosphorous acid is key to mastering its properties. Hypophosphorous acid, represented by the chemical formula \( H_3PO_2 \), is composed of one phosphorus atom, two oxygen atoms, and three hydrogen atoms.
When visualized, the chemical structure is often shown as HOP(O)H_2. This layout illustrates how the atoms are connected, making it clear where each atom fits into the molecule.

• The phosphorus atom is central to the structure.
• The arrangement gives an insight into the connectivity and relationship between these atoms.
• The structure highlights that not all hydrogen atoms are directly bonded to the phosphorus.

This configuration is important for understanding the reactivity and function of hypophosphorous acid.

Phosphorus Bonding

In hypophosphorous acid, the bonding of the phosphorus atom is quite intriguing. The phosphorus atom forms multiple bonds:

• It is bonded to two hydrogen atoms, which are directly attached to it.
• It is also bonded to one oxygen atom that further forms a bond with another, more electronegative oxygen atom.

The manner in which the phosphorus forms its bonds is crucial for determining the behavior of the compound.
Phosphorus having a lone pair in hypophosphorous acid makes it a pivotal element as it affects the molecule's overall acidity and how it reacts in different chemical processes.

Hydrogen Atoms

Hydrogen atoms in hypophosphorous acid play a unique role. With the formula \( H_3PO_2 \), the presence of three hydrogen atoms initially seems simple.
However, not all hydrogen atoms are directly involved with the central phosphorus atom.

• Two of these hydrogen atoms are directly connected to the phosphorus atom.
• The third hydrogen atom is connected through an oxygen atom.

Understanding the placement of these hydrogen atoms is essential because it influences the compound’s properties and its reactions, such as its acidity and how it may associate or react with other substances.
This specific arrangement highlights its unique physical characteristics and chemical reactivity, making hypophosphorous acid an interesting compound to study.