Why Does H3PO2 Have a Basicity of 1?

[Saitama]

Basicity is 1??

I was studying about Volumetric Analysis. In the chapter, there is a table which shows basicity of some acids. One is H₃PO₂. Its basicity is given as 1. But basicity of an acid is number of replacable hydrogen atoms present in one molecule of acid. So, bascitiy of H₃PO₂ should be 3. But that's not true according to book. It is 1.

 

[epenguin]

I was studying about Volumetric Analysis. In the chapter, there is a table which shows basicity of some acids. One is H₃PO₂. Its basicity is given as 1. But basicity of an acid is number of replacable hydrogen atoms present in one molecule of acid. So, bascitiy of H₃PO₂ should be 3. But that's not true according to book. It is 1.

You'd be right if you were talking about H₃PO₃.

 

[Saitama]

You'd be right if you were talking about H₃PO₃.

But why is its basicity 1?

 

[epenguin]

It looks like you are just confusing phosphoric acid where 3 H's are attached via O with hyopophorous acid where two H's are attached to P.

http://en.wikipedia.org/wiki/Hypophosphorous_acid

You are a lot less likely to ever meet the second, you are full enough of the first and esters and anhydrides of it in a very dynamic state.

 

[LudusRex]

I can confirm that the basicity of H3PO2 is indeed 1. This may seem confusing because H3PO2 has three hydrogen atoms, but the basicity of an acid refers to the number of hydrogen ions that can be donated in a chemical reaction. In the case of H3PO2, only one of the hydrogen atoms is able to dissociate and donate a proton, making its basicity 1. This is due to the unique molecular structure of H3PO2, which only allows one hydrogen ion to be released in a reaction. Therefore, the reported basicity of 1 for H3PO2 is accurate. It is important to remember that basicity is a property of an acid, not solely determined by the number of hydrogen atoms in its formula.