Acid–base Equilibria
The conjugate base of HSO₄⁻ is:
Select the correct option:
Solution
SO₄²⁻
According to the Brønsted–Lowry theory, a conjugate base is formed when an acid donates a proton (H⁺). HSO₄⁻ acts as an acid when it donates a proton: HSO₄⁻ → H⁺ + SO₄²⁻. Therefore, SO₄²⁻ is the conjugate base of HSO₄⁻. Note that HSO₄⁻ is amphoteric — it can act as an acid (losing H⁺ to form SO₄²⁻) or as a base (gaining H⁺ to form H₂SO₄). The conjugate acid-base pair is HSO₄⁻/SO₄²⁻. This concept is fundamental to understanding polyprotic acid dissociation, where H₂SO₄ undergoes stepwise ionisation with distinctly different Ka values for each step.
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About This Question
- Subject
- chemistry
- Chapter
- equilibrium
- Topic
- acid–base equilibria
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
SO₄²⁻
According to the Brønsted–Lowry theory, a conjugate base is formed when an acid donates a proton (H⁺). HSO₄⁻ acts as an acid when it donates a proton: HSO₄⁻ → H⁺ + SO₄²⁻. Therefore, SO₄²⁻ is the conjugate base of HSO₄⁻. Note that HSO₄⁻ is amphoteric — it can act as an acid (losing H⁺ to form SO₄²⁻) or as a base (gaining H⁺ to form H₂SO₄). The conjugate acid-base pair is HSO₄⁻/SO₄²⁻. This concept is fundamental to understanding polyprotic acid dissociation, where H₂SO₄ undergoes stepwise ionisation with distinctly different Ka values for each step.
This easy difficulty chemistry question is from the chapter equilibrium, covering the topic of acid–base equilibria. It appeared in the 2025 exam.
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