Strong vs Weak Acids
Chemistry: Cambridge International GCSE Supplement, topic 7.1.9
Strong vs Weak Acids
All acids ionise (become ions) in aqueous solutions. The strength of an acid is determined by how much it ionises in water. The strength of an acid is NOT the same as the concentration of an acid!
Strong acids
- Fully ionise in water, meaning that all of the acid molecules break up to form H+ ions.
- E.g. hydrochloric acid:
- HCl → H+ + Cl-
- Sulfuric and nitric acid are also strong acids.
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Weak acids
- Only partially ionise in water, meaning that not all of the acid molecules break up to form H+ ions.
- E.g. ethanoic acid (the main ingredient in vinegar):
- CH3COOH ⇌ CH3COO- + H+
- Most acids are weak acids.
Test yourself on Strong vs Weak Acids
Which is the stronger acid?
Why does the equation for ethanoic acid use the symbol ⇌ instead of →?