Identifying an amphoteric compound

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Steven Luong 1E
Posts: 33
Joined: Fri Apr 06, 2018 11:03 am

Identifying an amphoteric compound

Postby Steven Luong 1E » Wed Jun 06, 2018 10:49 pm

I know that an amphoteric compound has both acidic and basic characters, but can someone help me on how to identify them?

Toru Fiberesima 1L
Posts: 63
Joined: Fri Apr 06, 2018 11:02 am

Re: Identifying an amphoteric compound

Postby Toru Fiberesima 1L » Thu Jun 07, 2018 8:17 pm

If something has the ability to act as BOTH an acid and a base then it is amphoteric, so when looking at a reaction/equation, test if the compound has the ability to be a proton donor AND an hydroxide donor. One of the most common amphoteric substances out there is water as it behaves in this way.

EllenRenskoff-1C
Posts: 32
Joined: Fri Apr 06, 2018 11:04 am

Re: Identifying an amphoteric compound

Postby EllenRenskoff-1C » Thu Jun 07, 2018 9:54 pm

Is there a good way to tell just based on a molecular formula if a compound is amphoteric?

LilianKhosravi_1H
Posts: 32
Joined: Fri Apr 06, 2018 11:03 am

Re: Identifying an amphoteric compound

Postby LilianKhosravi_1H » Thu Jun 07, 2018 11:23 pm

what we did in discussion was create an equilibria where we used the amphoteric compound with water and tried to see if we could use it as both an acid and a base.
The example we did was H2PO3- :

using it as an acid = H2PO3- + H2O ⇌ (HPO3)2- + H3O+

using it as a base = H2PO3- + H2O ⇌ H3PO3 + OH-

so, since we can use H2PO3- as both a base and an acid in the transfer equilibria above, then it's an amphoteric compound.


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