Dmitrii Pyreu , Sergei Gridchin , Eugenii Kozlovskii
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引用次数: 0
Abstract
Based on pH-metric measurements, the equilibrium constants for ammonia protonation at 298.15 K and ionic strengths I = 5–9, supported by ammonium nitrate, were calculated. Using direct calorimetric measurements, the enthalpies of this process were determined at 288.15, 298.15 and 303.15 K and I = 5–9 and its full thermodynamic parameters were calculated. The sharp increase in exothermicity and decrease in entropy of this process observed at high ionic strengths are explained by decrease in the contribution of desolvation of reagents in the region of deficiency of solvent molecules and the influence of association of ions of background electrolyte. The obtained thermodynamic characteristics of ammonia protonation clearly indicate that a change in solvation state of reaction participants at high ionic strengths changes the nature of this reaction.
根据 pH 值测量结果，计算出了在 298.15 K 和离子强度 I = 5-9 条件下氨质子化的平衡常数，并得到了硝酸铵的支持。通过直接热量测量，确定了该过程在 288.15、298.15 和 303.15 K 及 I = 5-9 条件下的热焓，并计算了其全部热力学参数。在高离子强度下，该过程的放热率急剧上升，熵值急剧下降，这是因为在溶剂分子缺乏的区域，试剂的脱溶作用减弱，以及背景电解质离子结合的影响。所获得的氨质子化热力学特性清楚地表明，在高离子强度下，反应参与者溶解状态的变化改变了这一反应的性质。
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