Problem 4 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The oxoacid of sulphur that does not contain bond between Sulphur atoms is : [Main April 10, 2019 (I)] (a) \(\mathrm{H}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}\) (b) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{7}\) (d) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{4}\)

Step-by-Step Solution

Answer

The oxoacid \( H_2S_2O_7 \) (disulfuric acid) does not contain an S-S bond.

Step 1: Identify possible Sulphur-Sulphur bonds

Examine each oxoacid formula to determine if there is the possibility of a direct bond between Sulphur atoms. For an oxoacid formula written as \( H_2S_xO_y \), if \( x > 1 \), it may imply potential S-S bonding. However, not all \( x > 1 \) compounds have S-S bonds if they involve arrangments like chains or rings.

Step 2: Evaluate \\(H_2S_4O_6\\)

The molecular structure of \( H_2S_4O_6 \) (tetrathionic acid) features a chain of Sulphur atoms or an arrangement where Sulphur atoms are bonded directly. Thus, this oxoacid does contain S-S bonds.

Step 3: Evaluate \\(H_2S_2O_3\\)

In \( H_2S_2O_3 \) (thiosulfuric acid), one Sulphur atom is directly bonded to another Sulphur atom, forming an S-S bond. Therefore, this compound does have a direct Sulphur-Sulphur bond.

Step 4: Evaluate \\(H_2S_2O_7\\)

The structure for \( H_2S_2O_7 \) (disulfuric acid) involves a possible S-O-S linkage and does not require a direct bond between Sulphur atoms. Thus, this does not contain an S-S bond.

Step 5: Evaluate \\(H_2S_2O_4\\)

\( H_2S_2O_4 \) (dithionic acid) has an S-S single bond because it involves two Sulphur atoms directly linked. Hence, this compound contains an S-S bond.

Step 6: Identify the correct answer

The only option where no direct S-S bond exists is \( H_2S_2O_7 \), as it employs indirect linkages through oxygen atoms.

Key Concepts

Sulfur-Sulfur Bonding

Sulfur-sulfur bonding is a common feature in many sulfur-containing compounds, especially oxoacids. These bonds occur when two sulfur atoms link directly together. This creates a single bonded chemical structure.
Such bonding profoundly impacts the properties and reactivity of the compound.

• An example of sulfur-sulfur bonding is found in the structure of thiosulfuric acid ( \(\mathrm{H}_{2}\mathrm{~S}_{2}\mathrm{O}_{3}\)). Here, sulfur atoms are directly connected, forming a characteristic linkage.
• Another compound featuring sulfur-sulfur bonding is dithionic acid ( \(\mathrm{H}_{2}\mathrm{~S}_{2}\mathrm{O}_{4}\)), which also showcases direct sulfur connections.

Understanding whether sulfur atoms are connected directly helps in anticipating the potential reactivity of these molecules. It also plays a role in identifying unique chemical and physical characteristics.

Chemical Structures

Chemical structures provide important insights into the arrangements of atoms within a molecule. This includes which atoms are bonded together and how they are connected. In oxoacids, the structure is crucial as the arrangement of sulfur and oxygen can influence the properties of the acid.

• For example, tetrathionic acid ( \(\mathrm{H}_{2}\mathrm{~S}_{4}\mathrm{O}_{6}\)) is characterized by its long chain of sulfur atoms.
• Chemical formulas like \(\mathrm{H}_{2}\mathrm{~S}_{2}\mathrm{O}_{7}\) may suggest a linear sequence of sulfur and oxygen, particularly with sulfur atoms linked through oxygen instead of directly to each other.

Such structural information is vital for understanding chemical reactions. It also helps in predicting the behavior of the molecule under different conditions. Recognizing these structures can also guide chemists in synthesizing new compounds and exploring their potential applications.

Oxoacid Identification

Oxoacid identification involves analyzing the compound to understand its specific type and structure. It includes determining the presence of components like sulfur-sulfur bonds.

• A straightforward identification rule is examining the chemical formula: \(\mathrm{H}_{2}\mathrm{S}_{2}\mathrm{O}_{3}\) has more than one sulfur atom, indicating a potential for direct sulfur-sulfur bonding.
• Conversely, compounds like \(\mathrm{H}_{2}\mathrm{S}_{2}\mathrm{O}_{7}\) allow us to infer no direct S-S bond as sulfur is bonded through intervening oxygen atoms.

Correctly identifying oxoacids helps in understanding their function and role in various chemical processes. This includes processes like dissociation in water, redox reactions, or other applications. When sulfur is bonded indirectly, it typically results in different chemical behavior compared to compounds with direct sulfur-sulfur bonds. This impacts industrial uses and biological significance.