Strong and weak acids
Acids are graded by how readily they release H+ ions in water.
Strong acids
Ionise completely in water: every molecule splits into H+ ions and negative ions.
A hydrochloric acid solution holds no free HCl molecules — only H+ and Cl- ions.
Weak acids
Ionise only partly: only some of the molecules split into ions.
The rest stay dissolved as whole molecules.
Strong acids
HCl (aq) → H+ (aq) + Cl- (aq)
H2SO4 (aq) → 2H+ (aq) + SO42- (aq)
HNO3 (aq) → H+ (aq) + NO3- (aq)
Hydrochloric acid (HCl), sulphuric acid (H2SO4) and nitric acid (HNO3).
Weak acids
- Acetic acid (CH3COOH)
- Carbonic acid (H2CO3)
- Phosphoric acid (H3PO4)