Strong and weak acids
A strong acid fully splits into ions in water. A weak acid only partly splits. Strength is different from concentration.
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Analogy
A strong acid is a bag of sweets that is all handed out. A weak acid hands out only a few.
In practice
Hydrochloric acid is strong. Ethanoic acid, found in vinegar, is weak.
Practice
Flashcards
- What is the difference between a strong and a weak acid?A strong acid splits fully into ions. A weak acid only partly splits.
Interview questions
- Explain the difference between a strong acid and a concentrated acid.
- Strong means fully ionised in water
- Concentrated means lots of acid per unit of volume
- A weak acid can be concentrated
- A strong acid can be dilute
Questions people ask
Is a strong acid always more dangerous than a weak one?
Not always. Hazard depends on strength and concentration. A very concentrated weak acid can be harmful, while a very dilute strong acid may be fairly safe. Hydrochloric acid at the same concentration as ethanoic acid reacts faster because it has more free hydrogen ions.
How can you tell a strong from a weak acid in an experiment?
Compare solutions of the same concentration. The strong acid has a lower pH, reacts faster with magnesium and conducts electricity better, since it has more free ions. The weak acid has a pH closer to 7, such as 3 rather than 1.