Definition

[Madelyn Cearlock]

Can someone please explain and define amphoteric?

[Ava Kjos 1D]

Amphoteric means that a compound can behave as both an acid and a base. In general any of the metalloid oxides can be amphoteric. However, the most important example that you need to know is water...

Water as a base:

HCl(aq) + H2O(l) --> Cl-(aq) + H3O (aq)

Water behaves as a base in this case because it is receiving a proton (the H+) from HCl. According to Bronstein's definition, a molecule that receives a proton is a base and the molecule that donates a proton is an acid.

Water as an acid:

O^2-(aq) + H2O(l) --> 2OH-(aq)

In this case, water behaves as an acid because it donates a proton to O^2-.

[Kevin Tang 4L]

Another common example of an Amphoteric Compound is HCO3-

This is amphoteric because it can lose the H+ to form CO3^2- and it can also gain an H+ to form H2CO3

It just means it can both act as an acid and a base.

[Kirsty Star 2H]

Amphoteric simply means a compound that can act as either an acid or a base depending on the strength of the acid or base being added to it.

[Mallory_Podosin_1H]

Going off of this - can someone explain how we decide whether to use it as a base or an acid? Do you just have to look at the other reactant?

[Yixiao Hu 3C]

A substance which can act as either an acid or a base is described as being amphoteric.

[Dhwani Krishnan 1G]

Yes -an amphoteric substance like water would act like a base or an acid depending on what it is reacting with.