Strong acid — Science definition
An acid that ionizes completely in water, releasing nearly all of its hydrogen ions.
Where it is taught
- Acids & Bases — Acids, Bases & Titration, Physical Science: Chemistry, Grade 11
Questions using strong acid
Problem 1
Which statement correctly describes a strong acid?
- It is safe to taste because it is common
- It cannot conduct electricity
- It ionizes completely in water, releasing nearly all its H⁺
- It always has a pH above 7
Answer and explanation
It ionizes completely in water, releasing nearly all its H⁺
A strong acid ionizes essentially completely, releasing almost all of its hydrogen ions into solution.
Problem 2
Explain the difference between a strong acid and a concentrated acid.
Answer and explanation
'Strong' describes how completely the acid ionizes in water — a strong acid ionizes almost 100%. 'Concentrated' describes how much acid is dissolved per volume (a high molarity). The two are independent: you can have a dilute solution of a strong acid or a concentrated solution of a weak acid.
Problem 3
Which of these is a strong acid?
- acetic acid (CH₃COOH)
- citric acid
- hydrochloric acid (HCl)
- carbonic acid
Answer and explanation
hydrochloric acid (HCl)
Hydrochloric acid ionizes completely in water, making it a strong acid; the others are weak acids that ionize only partially.