OK..oil film expt..pipette/dropper a known aliquot of oil/meth solution onto a prepared water surface in a large basin. It's got lycopodium/talc powder scattered evenly over it to measure the area that the (hydrophylic) oil film will spread (A).
Say ur oil concn u made up is 1/50 parts oil:meths (meth is totally miscible with water). Measure say 100 such drops into a meas cylinder. Lets say the vol of 100 drops is 5cm^3.
Then 1 drop has vol of 0.05cm^3. This means the vol oil=V =0.05/50=0.001cm^3 oil.
Now measure the area of ur oil film. Use a sheet of mm graph paper. Let's say it's 500cm^2 (count the squares or if it's circular, use pi*r^2)
Assuming the oil spreads till it is 1 molecule thick, then size of molecule is t=V/A=0.001/500=2X10^-6cm=2x10^-8m (approx figs for say typical oil spec like stearic acid)
