 We're going to do an experiment to determine the number of molecules in a mole. We're going to do this by the monolayer method, creating a layer of oleic acid. We've created a small tray of water and we're going to put a small amount of pine pollen on the surface of the water to let us know where the layer is. We're going to add a dilute solution of oleic acid and alcohol. The alcohol will dissolve in the water and leave the oleic acid on the surface. The oleic acid will spread out into a layer that's one molecule thick. We're going to use a meter stick to measure some diameters of the layer. Since the layer is not regular, we're going to measure the diameter in several different directions and average the value. We will determine the number of drops of oleic acid solution per milliliter. To do this, we'll count the number of drops it takes to give us five milliliters and then we'll calculate how many drops it takes to give us one milliliter.