相图计算中杠杆规则运用值得注意的两个问题

Two Issues in the Using of Lever Rule in Phase Diagram

通过对两个例题的错误解答进行分析,提出了相平衡体系中运用杠杆规则值得注意的两个问题.一是两相体系中的液相饱和只是单一组份饱和,即体系对其中一个组份饱和时,对另一组分未必饱和;二是当体系中出现化合物时,若以物质的量表示体系组成,则会因为为计算基准发生变化,杠杆规则的表达形式必须作一定的修正.论文给出了修正后的杠杆规则计算式.

Based on the analysis of solutions of two examples,the author raised two questions about the using of lever rule in double phase systems.At first,in the bi-component double phase systems,when the liquid phase was relatively saturated by one constituent element,but not to the other element.The second,if chemical reaction was involved in the system,and we still describe systems construction in terms of amount-of-substance concentration,the basic computational unit shoud be changed.therefore the expression of lever rule must be revised.paper tells the revised formula.