Problem 53 - A Complete Resource Book in Chemistry for JEE Main

Question

The number of \(\mathrm{S}-\mathrm{S}\) bonds in sulphur trioxide is (a) zero (b) one (c) two (d) three

Step-by-Step Solution

Answer

The number of \(\mathrm{S}-\mathrm{S}\) bonds in sulfur trioxide is zero.

Step 1: Understanding Sulfur Trioxide Structure

Sulfur trioxide, denoted as \(SO_3\), is a compound consisting of one sulfur atom and three oxygen atoms. It is important to know that \(SO_3\) has no sulfur-sulfur \((\mathrm{S}-\mathrm{S})\) bonds as it consists solely of one sulfur atom. Understanding the structural formula helps to identify any potential \(\mathrm{S}-\mathrm{S}\) bonds.

Step 2: Identify Bond Types in Sulfur Trioxide

In \(SO_3\), the central sulfur atom forms double bonds with each of the three oxygen atoms. Thus, each oxygen is bonded to sulfur via a double bond. This structural arrangement leaves no room for \(\mathrm{S}-\mathrm{S}\) bonds in the molecule.

Step 3: Conclusion on Sulfur-sulfur Bonds

Since the structure of \(SO_3\) consists only of one sulfur atom, there is no possibility for any \(\mathrm{S}-\mathrm{S}\) bonds to exist. Each sulfur is bonded to the surrounding oxygen atoms, confirming that there are zero \(\mathrm{S}-\mathrm{S}\) bonds in sulfur trioxide.

Key Concepts

Bond Types in SO3

Sulfur trioxide (\(SO_3\)) is an intriguing compound due to its distinct bonding configuration. At its core, the sulfur atom needs to form bonds with three surrounding oxygen atoms. The type of bonds present in \(SO_3\) are known as covalent bonds, which involve the sharing of electrons between atoms. In \(SO_3\), each sulfur atom forms double covalent bonds with each of the three oxygen atoms.
Take note that double bonds are stronger and shorter than single bonds, contributing to the stability of the \(SO_3\) molecule. This arrangement allows sulfur to comply with the octet rule by reaching a stable electron configuration, where it uses available orbitals to share electrons with oxygen atoms in a robust arrangement.

S-S Bonds

S-S bonds are typically found in cases where there are two or more sulfur atoms bonded together. However, in the scenario of sulfur trioxide, \(SO_3\), there is only one sulfur atom present in the molecule, rendering the formation of \(S-S\) bonds impossible.
Since \(SO_3\) is composed of one sulfur atom bonded to three oxygen atoms, it doesn’t allow for any sulfur-sulfur connections.

• The absence of multiple sulfur atoms means that the usual S-S bonds found in molecules like elemental sulfur or polysulfides are not applicable in \(SO_3\).
• This specific lack of \(S-S\) bonds is pivotal for students to understand the structure and chemistry of sulfur trioxide.

SO3 Double Bonds

The presence of double bonds in sulfur trioxide is a fundamental aspect of its structure and reactivity. Each of the oxygen atoms in \(SO_3\) is connected to the central sulfur atom through a double bond. This specific configuration is what gives \(SO_3\) its planar molecular shape and contributes to its chemical properties.
Furthermore, these double bonds are characterized by the sharing of four electrons (two electron pairs) between the sulfur and each oxygen atom. This leads to a strong bond structure that maximizes the overlap of orbitals.

• The double bonds in \(SO_3\) are a key reason behind its relatively high level of reactivity and its ability to act as an acid anhydride, forming sulfuric acid when combined with water.
• This configuration also helps to minimize repulsion between electrons, maintaining the molecule’s stability.

By understanding the presence and role of these double bonds, students can better grasp the chemical nature of one of the most important oxides of sulfur used industrially.