alleryStart learning →The acid ionisation constant of a strong acid is described as:
AExactly equal to one
BImmeasurably small
CPrecisely equal to zero
DImmeasurably large
Answer & Solution
Correct answer: D. Immeasurably large
1. Ka is a ratio of ionised products to un-ionised acid.
2. For a strong acid the concentration of the un-ionised acid is zero.
3. Dividing by that vanishing quantity makes the constant immeasurably large.
4. That is why strong acid strengths are not usefully compared by Ka in water.
5. Weak acids, being only partially ionised, do have measurable constants.
_Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 14 'Acid-Base Equilibria', sections 14.1-14.7_
Keep practising Acid-Base Equilibria
Browse all Acid-Base Equilibria questions for AP Chemistry, or explore more Chemistry topics.
Related questions
Complete the strength ruleSort each gas by the acid it makesTrue or false: acids and basesMatch each acid-base termAcidic or basic at 25 C?Bicarbonate demonstrates amphiprotic behaviour because it can react with water as:Gay-Lussac concluded that acids and bases can be defined:Unlike Ka, the percent ionization of a weak acid typically changes when: