Related Experiment Video
Updated: May 29, 2026

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices
Published on: March 27, 2019
Calculation of contact angle on charged surface
1steve.chwastiak@alum.mit.edu
Abstract:
There is good correlation of contact angle measurements and contact angles calculated from surfactant adsorption density data for an electrically neutral surface, as reported in a previous paper for the system hematite-aqueous solution-ketone, with surfactant hexadecyl sulfonic acid. The same method is not sufficient when the hematite surface is electrically charged. Data was collected to develop the appropriate form of an electrostatic term for the analysis. Acid-base titration was used to evaluate surface electrical properties versus pH for the hematite used in the study. Surfactant adsorption isotherms were measured at pH of 4.5, 5.5, 6, and 7 to use in developing an equation for effect of surface potential on contact angle. After adding a term for the contribution of the electric field, the contact angles calculated from adsorption data follow the measured contact angles well.
Related Concept Videos
Contact Angle
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
Calculation of Electric Flux
Electric Field of a Charged Disk
The system's symmetry is in the cylindrical directions across the plane of the charge. As a result, the electric fields created by various surface charge elements nullify each other in the direction parallel to the surface. Thereby, the resulting electric field is perpendicular to the plane. Since the disk is...
Electric Field at the Surface of a Conductor
In the 19th century, Michael Faraday conducted the famous ice pail experiment to prove that the charges always reside on the surface of a conductor. The experimental set-up consists of a conducting uncharged container mounted on an insulating stand. The outer surface of the container is...
Gauss's Law: Problem-Solving
Gauss's Law: Planar Symmetry

