Definition of diprotic acid
one that contains within its molecular structure two hydrogen atoms per molecule capable of dissociating
Examples of diprotic acid in the following topics:
- Certain types of polyprotic acids have more specific names, such as diprotic acid (two potential protons to donate) and triprotic acid (three potential protons to donate).Let's take a quick look at a diprotic acid, oxalic acid, also called ethanedioic acid.
- As stated, oxalic acid is diprotic, having two protons to donate .If a dilute solution of oxalic acid were titrated with a sodium hydroxide solution, the protons would react in a stepwise neutralization reaction .If the pH of this titration were recorded and plotted against the volume of NaOH added, a very clear picture of the stepwise neutralization emerges .
- Each reaction proceeds with its unique value of Ka, affected by the pH environment and inductive effects of neutralization .An inorganic example of a triprotic acid is orthophosphoric acid (H3PO4), usually just called phosphoric acid.
- An organic example of a triprotic acid is citric acid, which can successively lose three protons to finally form the citrate ion.
- For example, a generic diprotic acid will generate three species in solution: H2A, HA-, and A2-.
- Polyprotic acids, also known as polybasic acids, are able to donate more than one proton per acid molecule.
- Specific types of polyprotic acids have more specific names, such as diprotic acid (two potential protons to donate) and triprotic acid (three potential protons to donate).
- Diprotic and polyprotic acids show unique profiles in titration experiments, where a pH versus titrant volume curve will clearly show two equivalence points for the acid.
- This is because the two ionization-capable hydrogen atoms on the acid molecule do not leave the acid at the same time.
- A diprotic acid (here symbolized by H2A) can undergo one or two dissociations depending on the pH.
- For example, a generic diprotic acid will generate 3 species in solution: H2A, HA-, and A2-.
- Diprotic and polyprotic acids contain multiple acidic protons that, regardless of chemical equivalence, each have unique acidic properties.
- Consider the case of a diprotic acid, such as sulfuric acid .