(B) A-B interactions

First let us introduce some notations:
= electron donor parameter or proton acceptor parameter (It is basically a measure of the propensity of the substance to donate an electron)
= electron acceptor parameter or proton donor parameter.

Here we see that can be negative.

For two materials, calculation of the interfacial tension between them requires the knowledge of six parameters that is three for each material.

For a material,

(2.17)

Surface tension may be affected by various factors.If the temperature increases, the interfacial tension also increases. Surface tension is also very sensitive to impurities. Presence of impurities generally decreases the surface tension.
The surface tensions of some frequently encountered liquids are listed in Table 2.

Table 2.1