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本文提出一个估算碱金属和碱土金属化合物标准熵的公式: S~0_(298)=∑S_i+S_r 经检验,计算结果与实验值符合良好。固体化合物标准熵的估算,以Latimer提出的离子熵加和法应用最为广泛。且有不少研究对该方法进行了改进和推广,但大多只限于单个离子熵值的确定方法。由于化合物的性质并不是各个离子性质的简单加和,这种简单加和法精度不可能达到令人满意的程度。对化合物标准熵实验值仔细分析便可得知,即使是离子性较强的碱金属化合物,不管对各个离子的熵值如何划分,就简单加和法而言,其平均偏差也不会低于1e.u。化合物的标准熵,是重要的热力学数据之一。如何更正确地估算各类化合物的标准熵对热力学计算和改进热化学数据库的预报与评价功能是非常有意义的。本文试图根据成键的概念,提出一个新的方法,以估算碱金属和碱土金属化合物的标准熵。
This paper presents a formula to estimate the standard entropy of alkali metal and alkaline earth metal compounds: S ~ 0 298 = ΣS_i + S_r After testing, the calculated results are in good agreement with the experimental data. The standard entropy estimation of solid compounds is the most widely used by Entropy addition method proposed by Latimer. And many researches have improved and popularized this method, but most of them are limited to the method of determining single ion entropy. Since the nature of the compound is not a simple summation of the individual ionic properties, the accuracy of this simple addition method can not be achieved to a satisfactory degree. A careful analysis of the standard entropic experimental values of the compounds shows that even in the case of the more ionic alkali compounds, the average deviation will not be less than the sum of the entropy values of the individual ions in the simple addition method 1e.u. The standard entropy of a compound is one of the important thermodynamic data. How to correctly estimate the standard entropy of various chemical compounds is of great significance for the thermodynamic calculation and improvement of the prediction and evaluation functions of the thermochemical database. This paper attempts to propose a new method based on the concept of bond formation to estimate the standard entropy of alkali metal and alkaline earth metal compounds.