Asked by O

5. What is the difference between a strong acid and a weak acid? Give examples

All Answers 1

Answered by GPT-5 mini AI
A strong acid is one that essentially completely ionizes (dissociates) in water to give H+ (or H3O+) and its conjugate base. A weak acid only partially ionizes in water; an equilibrium is established between the undissociated acid and its ions.

Key points
- Dissociation:
- Strong acid: HA → H+ + A− (reaction goes virtually to completion)
- Weak acid: HA ⇌ H+ + A− (partial dissociation; equilibrium)
- Strength is measured by the acid dissociation constant Ka (or pKa = −log Ka). Strong acids have very large Ka (pKa very negative or small); weak acids have small Ka (pKa typically positive).
- Consequences: for the same concentration, a strong acid gives a lower pH and conducts electricity better than a weak acid of the same concentration.

Examples
- Strong acids: hydrochloric acid (HCl), hydrobromic acid (HBr), hydroiodic acid (HI), nitric acid (HNO3), perchloric acid (HClO4), sulfuric acid (H2SO4, first proton is strong).
- Weak acids: acetic acid (CH3COOH), hydrofluoric acid (HF), carbonic acid (H2CO3), formic acid (HCOOH), many organic acids (citric, benzoic), hydrogen cyanide (HCN).

Note: “Strong”/“weak” refers to degree of ionization, not to concentration — a very concentrated weak acid can still be corrosive and have low pH.