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Difference between Amphoteric and Amphiprotic

Posted: Sat Nov 26, 2016 5:12 pm
by Josh_Zhong_1F
Hi,
What is the difference between Amphoteric and Amphiprotic?
Also, what is the relationship between Amphiprotic and Autoprotolysis?

Thanks,
Josh

Re: Difference between Amphoteric and Amphiprotic

Posted: Sat Nov 26, 2016 5:22 pm
by Emily Wang 1H
Both terms are describing properties of acids and bases, but amphiprotic is a bit more specific. Amphiprotic refers to a substance that can either gain or lose a proton, while amphoteric refers to a substance that can either be an acid or a base. However, there are multiple definitions for acids and bases (gaining/losing a proton in the Bronsted-Lowry model; gaining/losing electrons in the Lewis model) and the definition of amphoteric encompasses both of these definitions. Essentially, all amphiprotic substances are amphoteric but not all amphoteric substances are amphiprotic, because only the Bronsted-Lowry definition of acids and bases is based on gaining/losing protons.

Re: Difference between Amphoteric and Amphiprotic

Posted: Sat Nov 26, 2016 8:13 pm
by Tycho_Meimban_2B
Amphiprotic means the substance can both donate and accept a proton (H+).
Amphoteric refers generally to a substance that can act as an acid or as a base.

An example of a substance that is amphoteric is ZnO. ZnO cannot be considered amphiprotic since it cannot donate Hydrogen. However, due to the Lewis definition of acids and bases, ZnO is able to act as both an acid and a base.

All amphiprotic substances are amphoteric - since when they donate a proton they are acting as an acid, and when they accept a proton they are acting as base.

On the other hand, not all amphoteric substances are amphiprotic, because only in the Bronstead and Lowry sense do acids and bases only accept and donate protons.

Hope this isn't too complicated!