Classify if H^3PO^4 is a strong or weak acid, or strong or weak base, or salt?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

H3PO4 is commonly known as Phosphoric acid. As the name suggests, this compound is an acid. Generally an acid, is a proton donor, has a pH below 7, neutralizes base and turns blue litmus paper to red. This also means that in a solution (in water) H3PO4 produces Hydronium ions (H3O+ ions).

The chemical equation for the dissociation of Phosphoric acid (H3PO4) in the solution can be written as:

H3PO4(s)   + H2O(l)  --->H3O+(aq) + H2PO4−(aq)

H2PO4−(aq)+ H2O(l) <--->H3O+(aq) + HPO42−(aq) 

HPO42−(aq)+ H2O(l) <---> H3O+(aq) +  PO43−(aq) 

**H3PO4 contains 3 H's that can be protonated.


The first ionization (protonation) of Phosphoric acid can only be considered as strong acid.

Approved by eNotes Editorial Team

Posted on

Soaring plane image

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial