Sapling HW #2 [ENDORSED]

[Nayra Gharpetian 3F]

Can someone explain how to determine which substance is amphoteric? Here's the question:

Which of these substances is amphoteric, that is, it can act as a Brønsted acid and a Brønsted base?

BrO2^-
H3PO4
HBrO2
PO4^3-
H2PO4^-

[Ashley Ko 3I]

Hi! A substance can act as a Bronsted acid and Bronsted base if it has BOTH of the following: a H proton that it can donate (like an acid) and a negative charge so it can accept a H proton (like a base). Hope this helps!

[SainehaMaddineni_3I]

A Bronsted acid can donate H+, so there should be a Hydrogen in the formula. This leaves H3PO4, HBrO2, H2PO4^- to be possible answers. A Bronsted base can accept H+, which can be indicated by a negative charge as it allows the substance to accept an H+. Out of the 3 possible answers, H2PO4^- has a negative charge. Since it meets the descriptions of both Bronsted acid and Bronsted base, H2PO4^- is amphoteric.

[Nathaly Cruz 2D]

A Bronsted acid can donate H+, so there should be a Hydrogen in the formula. This leaves H3PO4, HBrO2, H2PO4^- to be possible answers. A Bronsted base can accept H+, which can be indicated by a negative charge as it allows the substance to accept an H+. Out of the 3 possible answers, H2PO4^- has a negative charge. Since it meets the descriptions of both Bronsted acid and Bronsted base, H2PO4^- is amphoteric.

Thank you for this explanation, it makes so much more sense now :)

[Mia Meza]

I was stuck on this one as well but you want to look for an H ion and a negative charge :)