Hydrogen chloride, bromide and iodide all appear equally strong in water. What is this effect called?
AThe levelling effect of water on them
BThe common ion effect between the acids
CThe salt effect of the dissolved halides
DThe buffering effect of the solvent used
Answer & Solution
Correct answer: A. The levelling effect of water on them
1. Water is a much stronger base than chloride, bromide or iodide.
2. So each of these acids gives up its proton to water essentially completely.
3. Complete ionisation for all three hides any real difference between them.
4. That inability to tell strong acids apart in water is the levelling effect of water.
5. In ethanol, a weaker base, the order of ionisation is hydrogen chloride, then bromide, then iodide.
_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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