Question

How many P-O-P linkage(s) is/are present in tetra polyphosphoric acid?

Answer 1

Hint: To solve this question first need to understand the concept of P-O-P linkage. Pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P-O-P linkage. So, based on this concept we will find out the linkages present in tetra polyphosphoric acid.

Complete step by step answer:
As we know that a pyrophosphate bond is referred to as a phosphoanhydride bond in which the naming convention emphasizes on the loss of water that occurs between two phosphates to form a new P-O-P bond. This bond mirrors the nomenclature for anhydrides of carboxylic acids.
Now, if we focus on the structure of tetra polyphosphoric acid then we know that it can be written as \[{H_6}{P_4}{O_{13}}\].

After that we will draw the structure and we can see that there are three P-O-P linkages present in tetra polyphosphoric acid.

Note:
After solving this, we need to remember that two or more orthophosphoric acid molecules can be joined through condensation into larger molecules by the elimination of water. With the process of condensation few units yield the polyphosphoric acids, while other larger molecules are known as polyphosphoric acids.
The backbone of any polyphosphoric acid molecule is a chain of alternating phosphorus and oxygen atoms. And each extra orthophosphoric unit that is condensed will add $1$ extra \[{\text{H}}\] that is, hydrogen atom, $1$ extra \[{\text{P}}\] that is, phosphorus atom, and \[3\] extra \[{\text{O}}\] that is, oxygen atoms.
Thus, the general formula of a polyphosphoric acid is ${H_{n + 2}}{P_n}{O_{3n + 1}}$
Also, these polyphosphoric acids are used in organic synthesis of cyclization and acylation.