Question

How does the miscibility of two surfactants mixed together affect the area per molecule at monolayer collapse?

Answer 1

You can find out the number of surfactant molecules in the spread solution from the parameters --

(i) The concentration of the solution and

(ii) Volume of the solution. You know the monolayer area (which is the area between the two barriers) from the software.

Then the area per molecule is just the monolayer area divided by the number of surfactant molecules. When you compress the monolayer area decreases but the number of surfactant molecules remains the same. Thus the area per molecule is decreased.

weight_spread = volume_spread*concentration

number of moles = weight_spread/molecular weight of sample

number of molecules spread = number of moles * 6.023*10^23(Avogadro. number)

mean molecular area = effective area of trough / number of molecules spread