Difference between 'amphiprotic and amphoteric?'?
Just for the purpose of a basic senior high school chemistry knowledge..level....whatever you call it.
- 1 decade agoFavorite Answer
Amphiprotic means the substance can both donate and accept a proton (H+), while amphoteric is a more general term meaning the substance can act as both an acid and a base. In a sense, water (H2O) can be considered both amphoteric and amphiprotic
H3O+ <------ H2O -----> -OH
here we see that water can potentially do both, gain a proton while acting as a base, and lose a proton while acting as an acid.
So, in a manner, 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. If you think about Lewis acids and bases - they either accept or donate electron lone pairs, which means that a substance that has more than one mechanism of action could do both a basic and an acidic thing - for example, a metal oxide such as Mg(OH)2, when placed in water can dissociate an -OH ion, which makes it a base, but the Mg can also have water coordinate to it with a lone pair, which makes it a Lewis acid.
Hope this helps.
- Anonymous1 decade ago
Both terms describe acids and bases however amphiprotic is a little more specific than amphoteric.
The definition of an acid or a base is more a description of how a chemical reacts rather than its actual structure, basically referring to whether a chemical gains or loses something in a reaction.
For most chemicals it is simple as they always react like an acid (e.g. HCl) or always like a base (NaOH). Amphoteric refers generally to a substance that can act as an acid or as a base.
The two major definitions of an acid are a substance that loses a proton in a reaction (Bronsted-Lowry) or a substance that gains an electron pair (Lewis). (And vice versa for a base)
Amphiprotic refers specifically to substances that can either lose or gain a proton in a reaction depending on the other substance, thereby acting as either acid or base under the Bronsted-Lowry definition, so amphiprotic substances always contain hydrogen.
Amphoteric then, refers to substances that can act as both acids and bases according to either definition whereas amphiprotic only refers specifically to substances that can be acid or base according to the B-L definition (proton transfers).
Water is the classic example of something that is both amphoteric and amphiprotic wheres as many metal oxides (e.g. ZnO, MgO) are only amphoteric.
Hope this is not too complicated
- 1 decade ago
An amphiprotic is an acid that donates 2 H+ ions such as H2SO4 or H3PO3
whereas an amphoteric is a substance that can behave as an acid as well as base such as Al2O3 and Zn2O3