Acetic Acid Dissociation in Water
CH3COOH + H2O ⇌ CH3COO− + H3O+
Overview
Acetic acid partially dissociates in water with Ka = 1.8 × 10⁻⁵, meaning only about 1.3% of molecules ionize in a 1 M solution. This equilibrium is the archetypal weak acid dissociation used to teach acid ionization constants, ICE tables, and the relationship between Ka and pH.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Acetic Acid CH₃COOH | 1 | (aq) |
| Reactant | Water H₂O | 1 | (l) |
Everyday Example
Vinegar (5% acetic acid) has a pH around 2.4 because the weak acid only partially ionizes, unlike strong acids that fully dissociate.
Industrial Importance
Understanding weak acid equilibria is essential for formulating buffer solutions, pharmaceutical preparations, and controlling pH in fermentation processes.
Properties
- Type
- Acid-Base
- Reversible
- Yes
- Energy
- Endothermic
- ΔH
- 0.4 kJ/mol
Related Reactions
Acetic Acid and Sodium Acetate Buffer System
Acetic Acid and Sodium Hydroxide Neutralization
Aluminum Chloride and Chloride Ion (Lewis Acid-Base)
Aluminum Hydroxide as Amphoteric Acid with NaOH
Aluminum Hydroxide as Amphoteric Base with HCl
Ammonia and Ammonium Chloride Buffer System
Ammonia and Hydrochloric Acid
Ascorbic Acid and Sodium Hydroxide
Barium Hydroxide and Ammonium Thiocyanate (Endothermic)
Benzoic Acid and Sodium Hydroxide
Frequently Asked Questions
What is the equation for Acetic Acid Dissociation in Water?
The balanced equation is: CH₃COOH + H₂O ⇌ CH₃COO⁻ + H₃O⁺.
What type of reaction is Acetic Acid Dissociation in Water?
Acetic Acid Dissociation in Water is a acid-base reaction. It is reversible under certain conditions.
Is Acetic Acid Dissociation in Water exothermic or endothermic?
Acetic Acid Dissociation in Water is endothermic (absorbs energy). The enthalpy change (ΔH) is 0.4 kJ/mol.