alleryStart learning →How does the acid ionisation constant of an acid relate to its strength?
AA smaller value marks the stronger acid
BThe value is the same for all weak acids
CThe value depends only on concentration
DA larger value marks the stronger acid
Answer & Solution
Correct answer: D. A larger value marks the stronger acid
1. The constant places the hydronium and conjugate base concentrations over the intact acid.
2. An acid that ionises further pushes more material into the numerator.
3. So a larger constant means a larger share of the acid has given up its proton.
4. That is exactly what is meant by a stronger acid.
5. The constant is fixed at a given temperature and does not vary with concentration.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.3 Relative Strengths of Acids and Bases_
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