How to calculate surface charge

[Huastecan]

Hi to all,

I have some polymers synthesized on nanometric scale with COOH groups. I want to calculate the surface charge density, the sample was characterized by means of a conductometric titration, with a dilute solution of NaOH, the analysis gave the equivalent of NaOH to the weak acid and the conductivity in mS/cm. I know the density and the surface area of the sample, but I do not know how to calculate the surface charge of the sample, it should give a result in C/nm2 or e/nm2. How can I calculate that data? I think I must use either the Gouy-Chapman theory or the Debye-Hücker theory.

 

[mark726]

Hello,

To calculate the surface charge density of your sample, you can use the Gouy-Chapman or Debye-Hücker theory. Both theories are commonly used to calculate the surface charge density of charged particles or surfaces.

The Gouy-Chapman theory is based on the concept of the electrical double layer, which is a layer of ions that forms around a charged surface. This theory takes into account the concentration of ions in the solution, the surface potential, and the distance from the surface to calculate the surface charge density.

The Debye-Hücker theory is similar to the Gouy-Chapman theory, but it also considers the ionic strength of the solution. This theory is more accurate for dilute solutions and takes into account the screening effect of ions in the solution.

To calculate the surface charge density using either theory, you will need to know the surface potential, which can be determined from the conductometric titration results. You will also need to know the surface area of your sample and the density of the COOH groups. From there, you can use the appropriate equations to calculate the surface charge density in C/nm2 or e/nm2.

I hope this helps. Best of luck with your calculations!