Size of Oil Molecule


When droplet of olive oil (oleic acid) is placed on water, oil spreads out until oil layer is 1 molecule high.

If the oil “spill” radius and the size of theĀ original droplet can be measured, one can estimate the length of the oil molecule.

Volume of original droplet = volume of oil spill pancake.

Use wire loop (diameter~1mm), to estimate volume of droplet (assume droplet is wafer, not sphere). Use calipers to measure.


Dip loop in olive oil.


Remove excess oil using paper towel.


Dust surface of water with lycopodium powder. This allows you to see clearly the final diameter of the spill. The larger the container the better.



Dip tip of wire loop into water. Oil immediately spreads out to form circle (very cool to watch!).

Measure diameter with ruler.0329171623

Should get order-of-magnitude accuracy.

  • Lycopodium powder and oil located in L35, corrosive materials cabinet (powder is safe to handle).
  • Tub located in L35.
  • Calipers located in L35, section D-2.
  • Tape measure in L35, section A-1.