What is the Charge on H3PO4? And Why?

The Charge of H3PO4 is 0.

But the question is how can you say that the charge on H3PO4 (Phosphoric acid) is 0?

Well you can say this by calculating its formal charge.

So let’s calculate the formal charge of H3PO4 (Phosphoric acid).

You can also refer to the below video from which you will learn to find charge of any ion.

Calculating the formal charge of H3PO4 using lewis structure

In order to calculate the formal charge on H3PO4 (Phosphoric acid), you should know the Lewis dot structure of H3PO4 (Phosphoric acid).

Here is the lewis structure of H3PO4.

Now using the above lewis structure of H3PO4, you have to find the formal charge on each atom that is present in the H3PO4 molecule.

For calculating the formal charge, you need to remember this formula;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

You can see the bonding and nonbonding electrons of H3PO4 from the image given below.

So now let’s calculate the formal charge on each individual atom present in H3PO4.

Formal charge on Hydrogen atom:
Valence electron = 1 (as it is in group 1 on periodic table) ^[1]
Nonbonding electrons = 0
Bonding electrons = 2

So according to the formula of formal charge, you will get;

Formal charge on Hydrogen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 1 – 0 – (2/2) = 0

So the formal charge on hydrogen atom is 0.

Formal charge on Phosphorus atom:
Valence electrons = 5 (as it is in group 15 on periodic table) ^[2]
Nonbonding electrons = 0
Bonding electrons = 10

So according to the formula of formal charge, you will get;

Formal charge on Phosphorus = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 5 – 0 – (10/2) = 0

So the formal charge on phosphorus atom is 0.

Now you can see that all the atoms of H3PO4 have 0 formal charge. 

This indicates that the overall H3PO4 (Phosphoric acid) molecule also has 0 charge and hence it is a neutral molecule.

I hope you have understood the above calculations for the formal charge of H3PO4 (Phosphoric acid). 

Check out some other related topics for your practice.

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Charge on Methane (CH4)
Charge of Antimony (Sb)
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Charge on HCN