alleryStart learning →How does the acidity of a hydrated metal ion depend on the ion itself?
AIt rises with higher charge and smaller size
BIt rises with higher charge and greater size
CIt rises with lower charge and smaller size
DIt rises with lower charge and greater size
Answer & Solution
Correct answer: A. It rises with higher charge and smaller size
1. The metal ion pulls electron density from the water molecules bound to it.
2. A larger positive charge pulls harder, so more protons are released.
3. A smaller ion concentrates that charge into less space, which also pulls harder.
4. So ionisation increases as the charge rises or as the ion shrinks.
5. This is why a triply charged aluminium ion is a stronger acid than a singly charged one.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.4 Hydrolysis of Salt Solutions_
Keep practising Acid-Base Equilibria
Browse all Acid-Base Equilibria questions for GCE A-Level (Singapore), or explore more Chemistry topics.
Related questions
Sort species into donor and acceptorTap the stronger acid each timeMatch each acid to its conjugate baseLine up three acids or three basesOver what pH range does methyl orange complete its colour change?What colour is phenolphthalein in a solution of pH below 8.3?Half the base needed for equivalence has been added to a weak acid. What is the pH of the What is the pH of 0.100 M acetic acid before any base is added, given Ka = 1.8 x 10^-5?