离子对液态水缔合构造影响的能量表征

摘要

利用差示扫描量热法(DSC),从能量变化的角度研究了在0-1.0 mol·L-1浓度范围内,KCl、MgCl2与CaCl2对液态水缔合构造的影响,并与17O-NMR化学位移δ(17OH2)的分析结果进行比较.随KCl、MgCl2与CaCl2浓度的升高,液态水的δ(17OH2)呈线性增加,而表观活化能(-E'/R)呈线性减小.并且δ(17OH2)与-E'/R对盐类浓度的变化率的大小满足如下顺序:KCl＜MgCl2＜CaCl2.基于二态模型,可以证明伴随盐类浓度的改变,液态水化学位移的变化量△δ与其摩尔内能的变化量△E满足线性关系.以上结果表明,KCl、MgCl2与CaCl2对水分子的构造化具有促进作用,在对水分子缔合构造的表征上,液态水的内能变化与17O-NMR化学位移具有等效性.%At a concentration of 0-1.0 mol ? L~1 the effect of salts (KCI, MgCI2, and CaCI2) on the structure of water was studied from the viewpoint of energy change using differential scanning calorimetry (DSC) and the results were compared with that obtained by the analysis of the chemical shift obtained by "O-NMR (5(1?OH2)). A linear increase in the 5(17OH2) of water and a linear decrease in the apparent activation energy (-BIR) of water with an increase in the concentration of salt was obtained. In addition, the rate of change of 5('7OH2) and -E'lR increased as follows: KCI