On-Line Controlled Calorimetry System and Its Application to Study on Complex Formation Equilibria between Zinc(II) and Thiocyanate Ions in Aqueous Solution
On-Line Controlled Calorimetry System and Its Application to Study on Complex Formation Equilibria between Zinc(II) and Thiocyanate Ions in Aqueous Solution
复制标题
在线控制量热系统及其在水溶液中锌(II)与硫氰酸根离子形成络合物平衡研究中的应用
DOI：
10.2116/analsci.1.263
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发表时间：
1985
影响因子：
1.6
通讯作者：
H. Ohtaki
中科院分区：
文献类型：
--
作者：
S. Ishiguro;Kiyoshi Yamamoto;H. Ohtaki
采用改进的全自动量热控制系统，旨在研究溶液中相对较弱的络合物形成平衡。在 25°C 下，在含有 5 mol dm^-3 NaClO_44 作为恒定离子介质的水溶液中，研究了锌 (II) 和硫氰酸根离子之间的络合物形成反应。获得的量热滴定曲线很好地解释了 [Zn(NCS)_n]^(2-n)+ ( n =1-4) 配合物的形成，并且确定了配合物的形成常数和形成焓。 [Zn(NCS)_2]配合物形成的第二步的逐步焓值和熵值比其他步骤的值更正，这表明溶剂化金属离子的水分子在第二步被广泛释放。
An improved fully automatic controlled system for calorimetry has been employed with the aim at studying relatively weak complex formation equilibria in solutions. Complex formation reactions between zinc(II) and thiocyanate ions have been investigated in an aqueous solution containing 5 mol dm^-3 NaClO_44 as a constant ionic medium at 25°C. Calorimetric titration curves obtained were well explained in terms of formation of the [Zn(NCS)_n]^(2-n)+ ( n =1-4) complexes, and the formation constants and enthalpies of formation of the complexes have been determined. The stepwise enthalpy and entropy values at the second step of formation of the [Zn(NCS)_2] complex were more positive than those at other steps, which suggested that water molecules solvating the metal ion were extensively liberated at the second step.