Question

How do you classify acids as strong and weak acids

Answer 1

Strong Acids

Strong acids completely dissociate in water, forming H+ and an anion. There are six strong acids. The others are considered to be weak acids. You should commit the strong acids to memory:

HCl - hydrochloric acid
HNO3 - nitric acid
H2SO4 - sulfuric acid
HBr - hydrobromic acid
HI - hydroiodic acid
HClO4 - perchloric acid


If the acid is 100% dissociated in solutions of 1.0 M or less, it is called strong. Sulfuric acid is considered strong only in its first dissociation step; 100% dissociation isn't true as solutions become more concentrated.

H2SO4 → H+ + HSO4-

Weak Acids

A weak acid only partially dissociates in water to give H+ and the anion. Examples of weak acids include hydrofluoric acid, HF, and acetic acid, CH3COOH. Weak acids include:

Molecules that contain an ionizable proton. A molecule with a formula starting with H usually is an acid.
Organic acids containing one or more carboxyl group, -COOH. The H is ionizable.
Anions with an ionizable proton. (e.g., HSO4- → H+ + SO42-)
Cations
Transition metal cations
Heavy metal cations with high charge
NH4+ dissociates into NH3 + H+