Difference Between Amphiprotic and Amphoteric

Amphiprotic vs Amphoteric

As amphiprotic and amphoteric are quite similar, the difference between amphiprotic and amphoteric too is quite confusing. Both of the terms, amphiprotic and amphoteric, are both related toacid-basechemistry. Amphoteric substances behave as an acid and as a base. All amphiprotic substances are able to donate and accept protons and can show both acid and base properties. Therefore, they are amphoteric too. This article describes the difference between amphiprotic substances and amphoteric substances in detail. Moreover, it gives examples and reactions to show their properties.

What are Amphiprotic Substances?

The term amphiprotic refers to the substances that can both accept and donate a proton; it can be eitherionic or covalent. Therefore, an amphoteric substance should have two main properties.

– The molecule must contain at least one hydrogen atom and it can be donated to another molecule.

– The molecule must contain a lone pair of electrons (electrons that are not involved in chemical bonding) to accept a proton.

Water (H₂O) is of the most common of amphiprotic substances; a water molecule satisfies both requirements needed for an amphiprotic substance.

In addition to water, most of the conjugated bases of diprotic acids can act as amphiprotic substances.

Diprotic Acid Conjugate Base

H₂SO₄HSO₄^–
H₂CO₃HCO₃^–
H₂S HS^–
H₂CrO₃HCrO₃^–

Example: Carbonic acid (H₂CO₃) is a weak diprotic acid, bicarbonate (HCO₃^–) is its conjugate base. In aqueous solutions,bicarbonateshows two types of reactions.

(1) Donating a proton to water (as a bronsted – Lowry acid)

HCO₃^–_(aq)+ H₂O —> H₃O⁺_(aq)+ CO₃^2-_(aq)

(2) Accepting a proton from water (as a bronsted – Lowry base)

HCO₃^–_(aq)+ H₂O —> H₂CO_3(aq)+ OH^–_(aq)

Therefore, bicarbonate (HCO₃^–) is an amphiprotic species.

What are Amphoteric Substances?

Substances that can act as both acid and base are called amphoteric substances. This definition is quite similar to amphiprotic substances. Because, all amphiprotic substances show acidic properties by donating a proton and similarly, they show basic properties by accepting a proton. Therefore, all the amphiprotic substances can be considered as amphoteric. However, the reverse statement is not always true.

We have three theories for acids and bases:

Theory Acid Base
ArrheniusH⁺producer OH^–producer
Bronsted-LowryH⁺donor H⁺accepter
Lewiselectron pair acceptor electron pair donor

Example: Al2O3 is a Lewis acid and a Lewis base. Therefore, it is an amphoteric substance, since it does not contain protons (H⁺), it is not an amphiprotic substance.

Al₂O₃as a base:

Al₂O₃+ 6 HCl —> 2 AlCl₃+ 3 H₂O

Al₂O₃as an acid:

Al₂O₃+ 2NaOH + 3 H₂O —> NaAl(OH)₄

两性的和放大器之间的区别是什么hoteric?

• An amphiprotic substance behaves as an acid and as a base. An amphoteric substance can accept or donate a proton (H⁺ion).

• All amphoteric substances are amphiprotic, but all amphiprotic substances are not amphoteric.

• Amphiprotic species consider the ability to donate or to accept a proton. However, amphoteric species consider the ability to act as an acid and as a base. Acid-base properties depend on three factors including the ability to donate or accept a proton.

If a substance possesses an electron pair to donate and it has the ability to accept an electron pair is considered as amphoteric.

If a substance has the ability to produce both H+ ion and OH- ion, it is considered as amphoteric.

Summary:

Amphiprotic vs Amphoteric

Amphoteric and amphiprotic substances are related to the acid-base chemistry. Both of these substances show acid and base properties. In other words, they can react as an acid and as a base depending on the other reactants. Amphiprotic substances can donate and accept a proton. Water is the most common example for an amphiprotic species. Most of the conjugated bases of diprotic acids also amphiprotic. Amphoteric substances can behave as an acid and as a base.