Acid–base Equilibria
Which equation correctly represents the autoionization of water?
Select the correct option:
Solution
2H2O ⇌ H3O+ + OH−
- Concept: Self-ionization of water occurs via proton transfer between molecules.
- Mechanism: One water molecule acts as an acid (donates H+) and another acts as a base (accepts H+).
- Reaction: H2O+H2O⇌H3O++OH−.
- Products: Hydronium ion (H3O+) and Hydroxyl ion (OH−).
- Simpler shorthand: Often written as H2O⇌H++OH−, but the balanced molecular form 2H2O⇌H3O++OH− is more physically accurate.
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About This Question
- Subject
- chemistry
- Chapter
- equilibrium
- Topic
- acid–base equilibria
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
2H2O ⇌ H3O+ + OH−
- Concept: Self-ionization of water occurs via proton transfer between molecules.
- Mechanism: One water molecule acts as an acid (donates H+) and another acts as a base (accepts H+).
- Reaction: H2O+H2O⇌H3O++OH−.
- Products: Hydronium ion (H3O+) and Hydroxyl ion (OH−).
- Simpler shorthand: Often written as H2O⇌H++OH−, but the balanced molecular form 2H2O⇌H3O++OH− is more physically accurate.
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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