Question

The number of \[S-O-S\]and $O-H$ links in ${{H}_{2}}{{S}_{2}}{{O}_{7}}$ molecule are respectively
A. 0,2
B. 1,2
C. 2,2
D. 2,1

Answer 1

Hint: ${{H}_{2}}{{S}_{2}}{{O}_{7}}$ is the formula for Oleum. Pyrosulfuric acid and disulfuric acid are other names for oleum. Oleum is known as sulfo hydrogen sulphate according to IUPAC.

Complete Step by Step Solution:
The primary component of fuming sulphuric acid is oleum. Compared to pyrosulphuric acid, sulphuric acid is a stronger acid. Bases and salts react to form salts like sodium and potassium pyrosulfate.

This acid can also be synthesised by reacting excess \[S{{O}_{3}}\] with sulphuric acid.
Some of the properties of Oleum are given below:
- Property values for the hydrogen bond acceptor and donor are 2 and 7, respectively. The number of rotatable bonds is 7.
- The boiling point of Oleum is \[36{}^\circ C\].
- The molecular weight of the compound is 178.129g/mol.
- The conjugate base given by Oleum is Disulphate.
- These were some of the properties of Oleum. Now, moving forward we’ll look at the applications of Oleum.

Applications of Oleum:
- The explosives and dyes are made up of Oleum.
- Another use of Oleum is as a sulfiting agent.
- It is consumed as a component in petroleum refining applications.

It can even cause irritation in eyes when exposed to Oleum and permanent tissue damage when swallowed.
The structure of Oleum that is ${{H}_{2}}{{S}_{2}}{{O}_{7}}$given as:

If we look at the structure there are different bonds between different atoms. Different bonds are like\[S-O-S\], $S=O$, \[S-OH\]. We can see there are 1\[S-O-S\] bonds, 4 $S=O$ bonds and 2\[S-OH\]bonds. We can see that oxygen is bonded to sulphur by a double bond and there is no \[S-S\]bond in this compound.
Hence, the correct option is B. 1,2 i.e. there are 1\[S-O-S\] bond and 2 $O-H$ linkage in ${{H}_{2}}{{S}_{2}}{{O}_{7}}$.

Note: In order to solve this question, the first thing to remember is the structure of ${{H}_{2}}{{S}_{2}}{{O}_{7}}$ because without that we cannot count any bond or types of bond. Another thing to remember is the presence of \[S-O-S\]. This is one of the very few oxoacids of sulphur that has this type of bonding.