Expert: Leo Carr - 7/14/2006

Question
I was eating and saw oil on the water's surface and wondered how do you separate oil from water? Is there some way to separate oil from water using lab procedures?  

Answer
Maryann,
 One simple way to separate the two would be by using their densities.  You know that water has a density of 1.0g/ml. Depending upon what kind of oil, (I'm thinking since you discovered it while eating it is consumable, such as vegatable oil, etc.).

 Typically, oil is less dense than water.  About 0.915 - 0.926g/mL.  So you can separate them.  You can let the water/oil mix just settle.  One way we do this in the lab is by a separatory funnel.  One component floats to the top and the other is on the bottom.  We can open the stopcock at the bottom of the flask and out comes one component.  Depending on which one we want, we can dicard the water (bottom layer) and keep the oil. (or vice versa)

Hope this helps.