Rucete ✏ Chemistry In a Nutshell
1. Bond Strength (H–X Bond)
- Acid strength increases as the H–X bond becomes weaker, making it easier to lose a proton (H⁺).
- Example order of increasing strength: HClO₄ > HI > HBr > HCl > H₂SO₄ > HNO₃
2. Bond Polarity
- The more polar the H–X bond, the easier it is to ionize → stronger acid.
- Order of decreasing polarity: HF > H₂O > NH₃ > CH₄
3. Size of X Atom
- Larger atoms form weaker H–X bonds, making the acid stronger.
- Acid strength increases down a group: HF < HCl < HBr < HI
4. Charge on the Acid/Base
- Acids with more negative charge tend to be weaker because negative charge resists proton loss.
- Example (phosphoric acid family): H₃PO₄ (pH 1.5) > H₂PO₄⁻ (pH 4.4) > HPO₄²⁻ (pH 9.3) > PO₄³⁻ (pH 12.0)
5. Oxidation State of the Central Atom
- Higher oxidation state = stronger acid, due to increased attraction of electron density, weakening the H–O bond.
- Example: HOCl < HOClO < HOClO₂ < HOClO₃
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Chemistry in a nutshell