Problem 183 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following Column-I (a) \(\mathrm{H}_{2} \mathrm{SO}_{5}\) (b) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{8}\) (c) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{6}\) (d) \(\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\) Column-II (p) S-S linkage (q) \(+6\) oxidation state (r) Peroxy linkage (s) \(-2\) oxidation state

Step-by-Step Solution

Answer

(a) matches (r, q), (b) matches (r, q), (c) matches (p), (d) matches (s).

Step 1: Identify the name of each compound

Each chemical formula in Column-I corresponds to a specific sulfur oxyacid: (a) \(\mathrm{H}_{2} \mathrm{SO}_{5}\) is peroxymonosulfuric acid (Caro's acid), (b) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{8}\) is peroxydisulfuric acid, (c) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{6}\) is dithionic acid, (d) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{3}\) is thiosulfuric acid.

Step 2: Assess each compound for linkage types

Check for specific linkages: (a) Peroxymonosulfuric acid \( (\mathrm{H}_{2} \mathrm{SO}_{5})\) contains a peroxy linkage \((\mathrm{O}-\mathrm{O})\), (b) Peroxydisulfuric acid \((\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{8})\) contains both a peroxy linkage \((\mathrm{O}-\mathrm{O})\) and \(+6\) oxidation state for sulfur, (c) Dithionic acid \((\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{6})\) has an S-S linkage, (d) Thiosulfuric acid \((\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{3})\) contains sulfur in the \(-2\) oxidation state.

Step 3: Determine oxidation states of sulfur

Determine the oxidation states where applicable: (a) In \(\mathrm{H}_{2} \mathrm{SO}_{5}\), sulfur is in the \(+6\) oxidation state. (b) In \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{8}\), both sulfur atoms are in the \(+6\) oxidation state. (c) In \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{6}\), sulfur atoms are in the \(+5\) oxidation state; hence there's no \(-2\) oxidation state option here. (d) In \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{3}\), one sulfur is \(+2\) and one is \(-2\).

Step 4: Perform the matching

Based on the analyses above, match as follows: (a) \(\mathrm{H}_{2} \mathrm{SO}_{5}\) with \(r\) and \(q\), (b) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{8}\) with \(r\) and \(q\), (c) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{6}\) with \(p\), (d) \(\mathrm{H}_{2}~\mathrm{S}_{2} \mathrm{O}_{3}\) with \(s\).

Key Concepts

Peroxy Linkage

The peroxy linkage is a special bond found in some sulfur oxyacids, involving an oxygen-oxygen single bond denoted as (O-O). This type of linkage is present in compounds like peroxymonosulfuric acid (Caro's acid) and peroxydisulfuric acid. These compounds exhibit unique chemical properties due to the presence of the peroxy bond, which is more reactive compared to standard oxygen compounds.
The presence of a peroxy linkage often makes these compounds suitable for use as powerful oxidizing agents.

• The peroxy linkage increases electrophilicity due to the extra oxygen, enhancing the compound's ability to act in oxidation reactions.
• These oxyacids are often used in industrial processes, like paper bleaching, that require strong oxidizers.

Understanding the presence and role of peroxy linkages can help predict the reactivity of compounds and their potential applications in chemical reactions.

Oxidation States

Oxidation states represent the theoretical charge of an atom if all bonds it forms with different elements were fully ionic. Understanding oxidation states is crucial in predicting chemical reactions and the behavior of molecules.
For sulfur oxyacids like those in the exercise:

• In peroxydisulfuric acid (h_22 s_22 o_88), sulfur typically exhibits a +6 oxidation state.
• Similarly, peroxymonosulfuric acid has sulfur in the +6 oxidation state.
• Dithionic acid and thiosulfuric acid show varying oxidation states, such as +5 in dithionic acid and mixed +2 and -2 states in thiosulfuric acid.

Determining the oxidation state involves accounting for the number of electrons lost or gained to reach a stable electronic configuration and helps in balancing chemical equations and understanding molecule stability.

S-S Linkage

S-S linkage, or disulfide linkage, involves a direct bond between two sulfur atoms. This is prominently observed in the structure of dithionic acid, represented as h_22 s_22 o_66.
The presence of S-S bonds gives compounds like dithionic acid distinctive properties.

• S-S linkages are central in biochemistry, such as stabilizing protein structures.
• For dithionic acid, this linkage is due to the oxidation of sulfur atoms creating a stable structure with an S-S bond.

These linkages result in molecular geometric patterns that contribute to the stability and reactivity of the compound, often being involved in redox reactions.

Thiosulfuric Acid

Thiosulfuric acid is an interesting sulfur oxyacid with the formula h_22 s_22 o_33. It involves a sulfur atom in a reduced state, with the sulfur atoms exhibiting both +2 and -2 oxidation states.
This compound showcases the versatility of sulfur's oxidation numbers:

• The thio prefix indicates the replacement of an oxygen atom by a sulfur atom, hence the presence of a lower oxidation state sulfur within the compound.
• It is less stable compared to other oxyacids and often appears in transient reactions or specific circumstances.

The unique property of having different oxidation states on sulfur within the same molecule offers fascinating insights into bonding and compound formation in acidic solutions.

Dithionic Acid

Dithionic acid, with the chemical formula h_22 s_22 o_66, exhibits an S-S linkage, and the involvement of sulfur in the +5 oxidation state.
Some essential features of dithionic acid include:

• The presence of S-S linkages giving rise to unique chemical and physical properties, making it a point of study in both organic and inorganic chemistry.
• Besides being observed in a narrow range of oxidative compounds, dithionic acid is of interest in redox chemistry, demonstrating reversible disulfide bond formation.

The presence of two sulfurs bonded together often leads to distinct chemical behavior, especially when these atoms are involved in higher oxidation states, impacting the overall reactivity and application of the compound in catalytic processes.