Practice question · Multiple choice
A 0.1 M solution of acetic acid has pH 2.9 while 0.1 M hydrochloric acid has pH 1. What does this show?
Hints
- The concentrations are identical, so the difference must lie elsewhere.
- Strength is the FRACTION that ionises, not the amount present.
Show the answer
B. Acetic acid ionises only partially at the same concentration
Why
Both solutions contain the same amount of acid. Hydrochloric acid ionises completely, giving M; acetic acid ionises only about 1 %, so its hydrogen-ion concentration is far lower. Strength and concentration are independent.
Practise Acids, Bases and pH
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