Zusammenfassung
Intradiffusion coefficients D-ii were measured for four binary systems with ammonia as one component by the pulsed field gradient NMR technique. The second components are: benzene, acetonitrile, I-pentanol and methanol. The studies are limited at the low temperature side by the onset of crystallisation. They are extended to a maximum pressure of 200 MPa. The concentration dependence of D-ii in ...
Zusammenfassung
Intradiffusion coefficients D-ii were measured for four binary systems with ammonia as one component by the pulsed field gradient NMR technique. The second components are: benzene, acetonitrile, I-pentanol and methanol. The studies are limited at the low temperature side by the onset of crystallisation. They are extended to a maximum pressure of 200 MPa. The concentration dependence of D-ii in the mixtures containing methanol, shows at constant T and p at lower temperatures a pronounced minimum in the D-ii vs. x curves. This minimum becomes deeper with increasing pressure. This can only be explained by the formation of transient hydrogen bonded networks in which the ammonia molecules participate as donors and acceptors. The data for the ammonia/methanol system are analysed by the mode coupling- and the VTF-models. Both show significant anomalies in the mole fraction range of ammonia x(NH3) approximate to 0.7.
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