Question

Why negative is written in front of surface excess concentration?

Answer 1

The surface excess concentration Γ is the area-related concentration of a surfactant at the surface or interface. It has the unit mol/m2.

Answer 2

Explanation:

Since it is now harder to create the new surface, the surface tension is higher. The general principle is: When the surface excess of a component is negative, increasing the chemical potential of that component increases the surface tension.