Which of the following is the strongest acid?
HBrO
HBrO4
HBrO3
HBrO2
The correct answer and explanation is :
The strongest acid among the given options is HBrO₄ (Perbromic acid).
Explanation:
Acid strength in oxyacids (acids containing oxygen) depends on two main factors:
- Oxidation State of the Central Atom
- In oxyacids of the same halogen (bromine in this case), the acid strength increases as the oxidation state of bromine increases.
- The oxidation states of bromine in the given acids are:
- HBrO (Hypobromous acid): +1
- HBrO₂ (Bromous acid): +3
- HBrO₃ (Bromic acid): +5
- HBrO₄ (Perbromic acid): +7
- A higher oxidation state means greater electron-withdrawing ability, leading to a more polar O-H bond and easier proton (H⁺) dissociation.
- Electronegativity and Inductive Effect
- More oxygen atoms increase the electronegativity of the molecule, pulling electron density away from the acidic hydrogen.
- This weakens the O-H bond, making it easier for the hydrogen ion to dissociate, increasing acidity.
- HBrO₄ has the most oxygen atoms, which means it has the strongest inductive effect, making it the strongest acid.
Conclusion:
Since HBrO₄ has the highest oxidation state (+7) and the most oxygen atoms, it is the strongest acid among the given choices.
Acid strength order:
HBrO < HBrO₂ < HBrO₃ < HBrO₄ (weakest to strongest).