离子对液态水缔合构造影响的能量表征

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’IR对盐类浓度的变化率的大小满足如下顺序:KCl22.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.

Energy Characterization of Effect for lons on the Structure of Water

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 ¹⁷O-NMR(δ(¹⁷OH₂)).A linear increase in theδ(^170OH₂ of water and a linear decrease in the apparent activation energy（-E’/R） of water with an increase in the concentration of salt was obtained.In addition, the rate of change ofδ(¹⁷OH₂) and -E’IR increased as follows:KCI22.Based on a two-state model,we demonstrate that the change inδ(¹⁷OH₂) of water（△δ） is proportional to the change in molar energy of water（△E）.These results indicate that KCI,MgCI₂,and CaCI₂ promote the formation of the water cluster structure and the energy change of water is equivalent to the chemical shift obtained by ¹⁷O-NMR for the characterization of the water cluster structure.