Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
seo-qna
SearchIcon
banner

Incorrect statement about pyrophosphorous acid H4P2O5 is:
(A) It contains P in +5 oxidation state.
(B) It is dibasic.
(C) It is strongly reduced in nature.
(D) It contains one POP bond.

Answer
VerifiedVerified
497.4k+ views
like imagedislike image
Hint: Pyrophosphorous acid H4P2O5 is an oxoacid of phosphorus. All the oxoacids of phosphorus have at least one P=O and one POH bond in their structure.

Complete step by step answer:
In oxoacids, phosphorus have four groups or atoms arranged in a tetrahedron. Structure of pyrophosphorous acid H4P2O5 is given below:

seo images

Some of the important characteristics of pyrophosphorous acid H4P2O5 are discussed below:
It is clear from the structure given above that H4P2O5 contains two P=O, two PH, two POH and one POP bond.
Oxidation state of P in H4P2O5 can be calculated as follows:
Let the oxidation state of P be ‘x’. Oxidation state of H is +1 and of O is taken as -2.
4×1+2x+5×(2)=0
4+2x10=0
2x6=0
x=3
Therefore, P is present in +3 oxidation state.
The OH bonds present in H4P2O5 are ionizable and give H+ ions. Basicity of oxoacids depends on the number of H+ ions. Thus, the basicity of H4P2O5 is 2 i.e. it is a dibasic acid.
Greater the number of PH bonds, stronger is the reducing agent. H4P2O5 contains two PH bonds thus, it is strongly reduced in nature.
Based on the above discussed points, it is clear that the oxidation state of phosphorus in pyrophosphorous acid is +3 and not +5.

So, the correct answer to the question is option (A).

Note: Carefully calculate the oxidation state and the number of different bonds present. Do not confuse pyrophosphorous acid with any other oxoacid of phosphorus.