Water Autoionization
H2O + H2O ⇌ H3O+ + OH−
Visão geral
Water undergoes autoionization where one molecule acts as an acid (donates H⁺) and another acts as a base (accepts H⁺). The equilibrium constant Kw = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25 C, defining pH 7 as neutral. This endothermic reaction shifts right at higher temperatures, decreasing neutral pH.
Participantes
| Papel | Substância | Coeficiente | Estado |
|---|---|---|---|
| Reagente | Water H₂O | 2 | (l) |
Exemplo do cotidiano
The pH scale itself is defined by water autoionization, which is why pH 7 is neutral at 25 C and why neutral pH changes at different temperatures.
Importância industrial
Compreender Kw é fundamental para toda a química aquosa, medição de pH, análise de qualidade da água e design de tampões.
Propriedades
- Tipo
- Acid-Base
- Reversível
- Sim
- Energia
- Endotérmico
- ΔH
- 55,8 kJ/mol
Reações relacionadas
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Carbonic Acid and Sodium Hydroxide
Aluminum Hydroxide as Amphoteric Acid with NaOH
Aluminum Chloride and Chloride Ion (Lewis Acid-Base)
Hydrochloric Acid and Sodium Hydroxide Neutralization
Nitric Acid and Potassium Hydroxide Neutralization
Hydrochloric Acid and Barium Hydroxide
Frequently Asked Questions
What is the equation for Water Autoionization?
The balanced equation is: H₂O + H₂O ⇌ H₃O⁺ + OH⁻.
What type of reaction is Water Autoionization?
Water Autoionization is a acid-base reaction. It is reversible under certain conditions.
Is Water Autoionization exothermic or endothermic?
Water Autoionization is endothermic (absorbs energy). The enthalpy change (ΔH) is 55.8 kJ/mol.