How Many Ionizable Hydrogen Atoms Are in Phosphorus Acid H3PO3?

[agoogler]

Homework Statement

What are the number of ionizable hydrogen atoms in phosphorus acid H₃PO₃?

Homework Equations

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The Attempt at a Solution

I didn't even know what "ionizable " means. ( This is not a homework questions, I'm solving sample questions for an entrance exam) . So I searched the web . But still I don't know how to decide the number of ionizable hydrogen atoms in H₃PO₃ . Please help.

 

[DrClaude]

Ionizable means that it can be made into an ion, which in the context of hydrogen in an acid means that it will liberate a H⁺ ion.

Have a look at http://en.wikipedia.org/wiki/Phosphorous_acid#Acid-base_properties. At most 2 hydrogen ions will leave phosphorus acid, leaving HPO₃^2-. Therefore, phosphorus acid has two ionizable hydrogen atoms.

 

[agoogler]

@DrClaude But if I'm just given a random acid how can I find the number of onizable hydrogen atoms?

 

[DrClaude]

You can't. It something you have to know: what are the common acids and how they react.