Monoprotic Acid
Definition and meaning of Monoprotic Acid in chemistry.
A monoprotic acid is an acid that donates exactly one proton (hydrogen ion, H+) per molecule in aqueous solution. Common monoprotic acids include hydrochloric acid (HCl), nitric acid (HNO3), and acetic acid (CH3COOH).
In more detail
In water, monoprotic acids undergo a single ionization step, releasing one H+ ion and one conjugate base anion. This simplicity makes monoprotic acids ideal for studying acid-base chemistry. Unlike polyprotic acids such as sulfuric acid (H2SO4) or carbonic acid (H2CO3), which can donate multiple protons, monoprotic acids have only one ionizable hydrogen. Monoprotic acids range from strong acids (like HCl and HNO3) to weak acids (like acetic acid and hydrofluoric acid), and are essential in analytical chemistry, industrial synthesis, and everyday applications from food preservation to cleaning.
Key facts
| Field | General Chemistry |
|---|---|
| Protons Released | One H+ ion per molecule |
| Common Examples | HCl, HNO3, CH3COOH |
| Contrast | Diprotic acids donate two protons; triprotic acids donate three |
Acetic acid (CH3COOH) is a weak monoprotic acid present in vinegar. When it dissolves in water, it donates a single proton to water, forming the acetate ion (CH3COO-) and a hydronium ion (H3O+).
Frequently asked questions
What is the difference between a monoprotic and a diprotic acid?
A monoprotic acid donates one proton per molecule, while a diprotic acid donates two protons per molecule. For example, hydrochloric acid (HCl) is monoprotic, but sulfuric acid (H2SO4) is diprotic.
Is acetic acid monoprotic?
Yes. Although the molecular formula CH3COOH contains four hydrogen atoms, only the carboxyl hydrogen (the one bonded to oxygen in the COOH group) ionizes. Therefore, acetic acid is monoprotic.