The quotient between the reduced surface pressure and the amphiphile mole fraction corresponds to the surface activity coefficient which is analogous to the bulk activity coefficient under the symmetric convention. This property indicates the ideal and non-ideal behavior of the bulk and surface phases. The main advantage of the construction followed in this work is that the contributions from the bulk and surface deviations from ideality can be separated into independent contributions. The non-ideality of the surface phase is not found in the volumetric phase. The natural logarithm of the surface activity coefficient as a function of the reduced surface pressure allows to identify different configurations of bulk and surface ideality or non-ideality.

Binary systems showing ideal behavior in the surface and bulk phases, non-ideal behavior in the surface but ideal behavior in the bulk phase, ideal behavior in the surface and non-ideal behavior in the bulk phase, and systems exhibiting non-ideal behavior in both regions are analyzed and compared with experimental data and classified with the presented model..

降低的表面压力与两亲物摩尔分数之间的商对应于表面活度系数，其类似于对称惯例下的体积活度系数。此属性表示体相和表面相的理想和非理想行为。在这项工作中遵循的构造的主要优点是可以将来自理想状态的体积和表面偏差的贡献分离为独立的贡献。在体积相中没有发现表面相的非理想性。作为减小的表面压力的函数的表面活性系数的自然对数允许识别体积和表面理想或非理想的不同配置。

二元系统在表面和体相中表现出理想行为，在表面中表现出非理想行为但体相中表现出理想行为，表面中表现出理想行为而体相中表现出非理想行为，以及在体相中表现出非理想行为的系统对这两个区域进行分析并与实验数据进行比较，并用所提出的模型进行分类。