Amphiprotic compounds

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Katherine Fitzgerald 1A
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Amphiprotic compounds

Postby Katherine Fitzgerald 1A » Sun Jul 28, 2019 11:22 am

In 6A12, we are asked to write chemical equations of two proton transfer equilibria that demonstrate the amphiprotic character of NH3. However, in 6A13, we are told to identify NH3 as either an acid or a base. I would think if it is amphiprotic, the answer would be "both", or it depends on the situation. However, the answer is that it is a base. I can see visually it has a lone pair, and so that makes sense. How do you square that it is both a base AND amphiprotic?

Also, do we need to memorize which compounds are amphiprotic?

Do we need to be able to predict whether an amphiprotic compound will give off or accept a proton in a given reaction? If so, how you do this?

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Re: Amphiprotic compounds

Postby Chem_Mod » Sun Jul 28, 2019 2:30 pm

NH3 is amphiprotic because if put in water, it can donate a proton and become NH2- and the water becomes H3O+. OR, it could accept a proton and become NH4+ and water becomes hydroxide OH-.

Typically an amphiprotic would have at least a Hydrogen to begin with so that it could donate it or it could accept one if it could become a polyprotic acid.

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