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Las cavidades en líquidos moleculares y la teoría de las solubilidades hidrofóbicas
1Department of Chemistry, University of California, Berkeley 94720, USA.
Journal of the American Chemical Society
|January 1, 1990
Resumen
Este estudio revela que el agua líquida es agua líquida.
Área de la Ciencia:
- Química Física es la química física.
- Química computacional es la química computacional.
- Ciencia de la Solvación Ciencia de la Solvación.
Sus antecedentes:
- Comprender los efectos del disolvente en el comportamiento del soluto es crucial en química.
- Las diferencias en la solvación entre el agua y los disolventes orgánicos a menudo se atribuyen a la estructura única de enlaces de hidrógeno del agua.
- Una hipótesis alternativa sugiere que el tamaño molecular juega un papel más significativo.
Objetivo del estudio:
- Para investigar el trabajo de formación de cavidades de tamaño atómico en varios disolventes moleculares.
- Para probar la hipótesis de que el tamaño molecular, en lugar de la unión de hidrógeno, explica principalmente las diferencias de solvación entre el agua y los disolventes no acuosos.
- Para comparar las características de volumen libre del agua líquida con los disolventes de esfera dura.
Principales métodos:
- Se utilizaron datos de configuración térmica de líquidos puros.
- Calculó el trabajo de formación de cavidades esféricas duras de tamaño atómico.
- Empleó el modelo de partículas a escala para predecir la solubilidad del gas inerte en agua líquida.
Principales resultados:
- El agua líquida exhibe un mayor volumen libre fraccionado, pero se distribuye en bolsas más pequeñas en comparación con los disolventes orgánicos.
- El trabajo de formación de cavidades en el agua difiere significativamente del de disolventes orgánicos comparables.
- El modelo de partículas a escala subestimó el trabajo de cavidad en el agua TIP4P en aproximadamente un 20% para cavidades de tamaño atómico.
Conclusiones:
- Las diferencias estructurales en la distribución del volumen libre, no sólo en la unión de hidrógeno, son clave para entender la disolución en agua.
- El tamaño molecular más pequeño del agua conduce a una formación de cavidades menos favorable para los gases inertes en comparación con los disolventes de moléculas más grandes.
- Las cavidades de tamaño atómico deben considerarse submacroscópicas en el contexto de las estructuras líquidas.
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