Found an error in one of the resource tests! (1 Viewer)

[OToole]

Doonside Technology HS '01 Trial Exam:

Question 17)

Consider the following ions: CH3COO-, NH4+ and HPO4 2-

a) Which of the ions above can act as an amphiprotic species?


Now to me I don't think this question has an answer.
HPO4 seems to be the only real possibility (even though I have never encountered it), but when looking at the solutions I notice that the student had answered this, yet been marked wrong.

I don't think that CH3COO- NH4+ are amphiprotic (well I know they aren't) as they are buffer solutions in conjugate acid-base pairs. NH4+ cannot accept a proton and CH3OO- cannot donate one.

The only think I can think of is that the P should have been an S as HSO4 is indeed amphiprotic.
Of course I could be way off, anyone want to concur with/guide me?
[FONT=&quot]Cheers.[/FONT]

 

[Riviet]

NH4+ cannot accept a proton and CH3OO- cannot donate one.

Your reasoning here is correct. Also HPO₄^2- IS an amphiprotic species because it can accept a proton to become H₂PO₄^- or donate a proton to become PO₄^3-.