Recently, I have been trying to study surface chemistry and I have come across questions that I do not understand how to answer. I understand what a dipole moment is, defined as a charge separation over a defined distance, and I have a fair understanding of surfactants and other areas of surface chemistry such as Langmuir Isotherms. But I am struggling to answer such questions:
- How would surfactants with a dipole moment in contact with water be characterised?
Would this mean that most likely the ionic head of a surfactant interacts with either the partially-positive hydrogen or partially-negative oxygen moiety of a water molecule? If so, what would be the proper way to characterise this phenomenon?
- In what phase of the monomolecular layer are the sizes of surfactants determined?
I am puzzled by this question, as I do not understand what exactly is meant by phase. I have spent relentless time trying to search for monomolecular layers and their phases but I have come out empty-handed. I see that phase can refer to distinct boundaries of physical states, such as those between gasses and liquids, but I do not know how this could be used to find the size of molecules. I know that in order to find the area that each surfactant molecule covers at an interface the Gibbs Adsorption Equation is utilised, however it uses concentration of surfactant molecules plotted against surface tension.
I would be much obliged if anyone could provide assistance to aid me in understanding this subject of surface chemistry better.